Disease-causing Mutations (disease-causing + mutation)

Distribution by Scientific Domains


Selected Abstracts


Buried water molecules in helical transmembrane proteins

PROTEIN SCIENCE, Issue 2 2008
Robert Renthal
Abstract Buried water molecules (having no contact with bulk solvent) in 30 helical transmembrane (TM) protein structures were identified. The average amount of buried water in helical TM proteins is about the same as for all water-soluble (WS) proteins, but it is greater than the average for helical WS proteins. Buried waters in TM proteins make more polar contacts, and are more frequently found contacting helices than in WS proteins. The distribution of the buried water binding sites across the membrane profile shows that the sites to some extent reflect protein function. There is also evidence for asymmetry of the sites, with more in the extracellular half of the membrane. Many of the buried water contact sites are conserved across families of proteins, including family members having different functions. This suggests that at least some buried waters play a role in structural stabilization. Disease-causing mutations, which are known to result in misfolded TM proteins, occur at buried water contact sites at a higher than random frequency, which also supports a stabilizing role for buried water molecules. [source]


Crystallization and preliminary X-ray studies of the N-domain of the Wilson disease associated protein

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2009
Lili Liu
Wilson disease associated protein (ATP7B) is essential for copper transport in human cells. Mutations that affect ATP7B function result in Wilson's disease, a chronic copper toxicosis. Disease-causing mutations within the N-domain of ATP7B (WND) are known to disrupt ATP binding, but a high-resolution X-ray structure of the ATP-binding site has not been reported. The N-domain was modified to delete the disordered loop comprising residues His1115,Asp1138 (WND,1115,1138). Unlike the wild-type N-domain, WND,1115,1138 formed good-quality crystals. Synchrotron diffraction data have been collected from WND,1115,1138 at the Canadian Light Source. A native WND,1115,1138 crystal diffracted to 1.7,Å resolution and belonged to space group P42212, with unit-cell parameters a = 39.2, b = 39.2, c = 168.9,Å. MAD data were collected to 2.7,Å resolution from a SeMet-derivative crystal with unit-cell parameters a = 38.4, b = 38.4, c = 166.7,Å. The WND,1115,1138 structure is likely to be solved by phasing from multiwavelength anomalous diffraction (MAD) experiments. [source]


Prioritizing regions of candidate genes for efficient mutation screening,

HUMAN MUTATION, Issue 2 2006
Terry A. Braun
Abstract The availability of the complete sequence of the human genome has dramatically facilitated the search for disease-causing sequence variations. In fact, the rate-limiting step has shifted from the discovery and characterization of candidate genes to the actual screening of human populations and the subsequent interpretation of observed variations. In this study we tested the hypothesis that some segments of candidate genes are more likely than others to contain disease-causing variations and that these segments can be predicted bioinformatically. A bioinformatic technique, prioritization of annotated regions (PAR), was developed to predict the likelihood that a specific coding region of a gene will harbor a disease-causing mutation based on conserved protein functional domains and protein secondary structures. This method was evaluated by using it to analyze 710 genes that collectively harbor 4,498 previously identified mutations. Nearly 50% of the genes were recognized as disease-associated after screening only 9% of the complete coding sequence. The PAR technique identified 90% of the genes as containing at least one mutation, with less than 40% of the screening resources that traditional approaches would require. These results suggest that prioritization strategies such as PAR can accelerate disease-gene identification through more efficient use of screening resources. Hum Mutat 27(2), 195,200, 2006. © 2006 Wiley-Liss, Inc. [source]


A T3 allele in the CFTR gene exacerbates exon 9 skipping in vas deferens and epididymal cell lines and is associated with Congenital Bilateral Absence of Vas Deferens (CBAVD),

HUMAN MUTATION, Issue 1 2005
Antoine Disset
Abstract The different alleles at the (TG)m(T)n polymorphic loci at the 3, end of the human CFTR intron 8 determine the efficiency by which exon 9 is spliced. We identified a novel TG12T3 allele in a congenital bilateral absence of vas deferens (CBAVD) patient who carries a [TG11T7; p.Phe508Cys; p.Met470Val] haplotype on the other chromosome. To better understand the complex regulation of exon 9 splicing, we analyzed the levels of correctly spliced CFTR transcripts in six CFTR-expressing epithelial cell lines derived from lung, colon, testis, vas deferens, and epididymis transiently transfected with four CFTR minigenes (pTG11T7, pTG12T7, pTG12T5, and pTG12T3). In this work, we show that a decrease in the Ts at the polymorphic locus in a TG12 background determines a cell-type dependent reduction in exon 9+ transcripts that is not related to the basal splicing efficiency in the cell line. These data emphasize the role of the T5 allele in CBAVD and identify the T3 allele as a severe cystic fibrosis (CF) disease-causing mutation. Finally, UV cross-linking experiments demonstrated that tissue-specific trans -acting splicing factors do not contribute to the different patterns of exon 9 splicing found between the cell lines. However, we observed that lower numbers of Ts can alter the binding of TDP-43 (TDP43 or TARDBP) to its specific target ug12 in a tissue-specific manner. Our results support the idea that the ratio of general splicing factors plays a role in the tissue variability of exon 9 alternative splicing. Hum Mutat 25:72,81, 2005. © 2004 Wiley-Liss, Inc. [source]


A somatic NLRP3 mutation as a cause of a sporadic case of chronic infantile neurologic, cutaneous, articular syndrome/neonatal-onset multisystem inflammatory disease: Novel evidence of the role of low-level mosaicism as the pathophysiologic mechanism underlying mendelian inherited diseases

ARTHRITIS & RHEUMATISM, Issue 4 2010
Juan I. Aróstegui
Objective Chronic infantile neurologic, cutaneous, articular syndrome (CINCA), also known as neonatal-onset multisystem inflammatory disease (NOMID), is a severe, early-onset autoinflammatory disease characterized by an urticaria-like rash, arthritis/arthropathy, variable neurologic involvement, and dysmorphic features, which usually respond to interleukin-1 blockade. CINCA/NOMID has been associated with dominant Mendelian inherited NLRP3 mutations. However, conventional sequencing analyses detect true disease-causing mutations in only ,55,60% of patients, which suggests the presence of genetic heterogeneity. We undertook the current study to assess the presence of somatic, nongermline NLRP3 mutations in a sporadic case of CINCA/NOMID. Methods Clinical data, laboratory results, and information on treatment outcomes were gathered through direct interviews. Exhaustive genetic studies, including Sanger method sequencing, subcloning, restriction fragment length polymorphism assay, and pyrosequencing, were performed. Results The patient's CINCA/NOMID was diagnosed based on clinical features (early onset of the disease, urticaria-like rash, knee arthropathy, and dysmorphic features). The patient has exhibited a successful response to anakinra within the last 28 months. Analysis of NLRP3 identified a novel heterozygous variant (p.D303H) that was detected in ,30,38% of circulating leukocytes. The absence of this variant in healthy controls and in the patient's parents suggested a de novo true disease-causing mutation. Additional analyses showed that this novel mutation was present in both leukocyte subpopulations and epithelial cells. Conclusion Our findings identify the novel p.D303H NLRP3 variant in a Spanish patient with CINCA/NOMID as a new disease-causing mutation, which was detected as a somatic, nongermline mutation in hematopoietic and nonhematopoietic cell lineages. Our data provide new insight into the role of low-level mosaicism in NLRP3 as the pathophysiologic mechanism underlying cryopyrin-associated periodic syndrome. [source]


NOD2-Associated pediatric granulomatous arthritis, an expanding phenotype: Study of an international registry and a national cohort in spain

ARTHRITIS & RHEUMATISM, Issue 6 2009
Carlos D. Rosé
Objective To study the phenotype characteristics of the largest to date cohort of patients with pediatric granulomatous arthritis (PGA) and documented mutations in the NOD2 gene. Methods We analyzed merged data from 2 prospective cohorts of PGA patients, the International PGA Registry and a Spanish cohort. A systematic review of the medical records of interest was performed to identify phenotype characteristics. Results Forty-five patients with PGA (23 sporadic cases and 22 from familial pedigrees) and documented NOD2 mutations were identified and formed the basis of the study. Of these 45 patients, 18 had the R334W-encoding mutation, 18 had R334Q, 4 had E383K, 3 had R587C, 1 had C495Y, and 1 had W490L. The majority of patients manifested the typical triad of dermatitis, uveitis, and arthritis. In contrast, in 13 patients, the following "atypical" manifestations were noted: fever, sialadenitis, lymphadenopathy, erythema nodosum, leukocytoclastic vasculitis, transient neuropathy, granulomatous glomerular and interstitial nephritis, interstitial lung disease, arterial hypertension, hypertrophic cardiomyopathy, pericarditis, pulmonary embolism, hepatic granulomatous infiltration, splenic involvement, and chronic renal failure. In addition, 4 individuals who were asymptomatic carriers of a disease-causing mutation were documented. Conclusion NOD2 -associated PGA can be a multisystem disorder with significant visceral involvement. Treating physicians should be aware of the systemic nature of this condition, since some of these manifestations may entail long-term morbidity. [source]


PYPAF1 nonsense mutation in a patient with an unusual autoinflammatory syndrome: Role of PYPAF1 in inflammation

ARTHRITIS & RHEUMATISM, Issue 2 2006
I. Jéru
Objective To gain insight into the pathophysiology of an unusual autoinflammatory syndrome, in a patient of Armenian origin, that mimicked familial Mediterranean fever (FMF) but with episodes triggered by generalized exposure to cold, and to further elucidate the controversial function of the protein encoded by PYPAF1, whose mutations (exclusively missense to date) have been identified in 3 hereditary recurrent fever syndromes. Methods The patient's DNA was screened for mutations in both MEFV, the gene responsible for FMF, and PYPAF1. The ability of different recombinant PYPAF1 isoforms, expressed in HEK 293 cells, to regulate NF-,B signaling was subsequently assessed. Results No disease-causing mutation was found in MEFV. However, a nonsense mutation (p.Arg554X) was identified in PYPAF1; this defect resulted in a truncated protein lacking all leucine-rich repeats. Study of the wild-type and mutant PYPAF1 recombinant proteins revealed that PYPAF1 inhibited NF-,B proinflammatory pathways, and that the identified nonsense mutation impaired this property. Conclusion These molecular and clinical findings, together with the clinical manifestations in the patient, which call into question the current nosology of the hereditary recurrent fever syndromes, are consistent with the hypothesis that PYPAF1 acts as an inhibitor of NF-,B signaling. They also provide a clear elucidation of the functional consequences of this nonsense PYPAF1 mutation not previously described in the literature, which result in a partial loss of function and may thereby explain the pathophysiology of the autoinflammatory syndrome observed in this patient. [source]


Elastosis perforans serpiginosa-like pseudoxanthoma elasticum in a child with severe Moya Moya disease

BRITISH JOURNAL OF DERMATOLOGY, Issue 2 2005
S. Meyer
Summary A 2-year-old girl with Moya Moya disease who had relapsing cerebrovascular strokes presented with loose skin folds, ,chicken' skin appearance and perforating elastosis serpiginosa-like lesions in the genitocrural region. Histologically, calcified material perforating the epidermis and adjacent short curled and mineralized elastic fibres suggested a variant of pseudoxanthoma elasticum (PXE). As PXE is known to be caused by various mutations in the transmembrane transporter ABCC6 gene, we hypothesized that a novel ABCC6 mutation may underlie this unique combination of PXE and elastopathic vascular damage. Therefore, the complete ABCC6 coding region of the patient and her parents was screened for genetic alterations. No bona fide disease-causing mutation of ABCC6 could be found in the child and in her parents. However, two novel allelic amino acid substitutions (Arg1273Lys and Glu1293Lys; exon 27) were found in the girl and her father, localized in close proximity to the region that codes for the functionally critical second nucleotide-binding fold of ABCC6. Although a causal involvement of these amino acid substitutions could not be proven based on this study, both heterozygote substitutions may possibly have interacted with other undetected recessive maternal ABCC6 changes in the child. To the best of our knowledge, this is the first report of an association between early-onset PXE and severe Moya Moya syndrome possibly related to ABCC6 changes. [source]


Cardiac troponin T Arg92Trp mutation and progression from hypertrophic to dilated cardiomyopathy

CLINICAL CARDIOLOGY, Issue 5 2001
Noboru Fujino M.D.
Abstract Background: Mutations in the cardiac troponin T gene causing familial hypertrophic cardiomyopathy (HCM) are associated with a very poor prognosis but only mild hypertrophy. To date, the serial morphologic changes in patients with HCM linked to cardiac troponin T gene mutations have not been reported. Hypothesis: The aim of this study was to determine the long-term course of patients with familial HCM caused by the cardiac troponin T gene mutation, Arg92Trp. Results: The Arg92Trp missense mutation was present in 10 individuals from two unrelated pedigrees. They exhibited different cardiac morphologies: three had dilated cardiomyopathy-like features, five had asymmetric septal hypertrophy with normal left ventricular systolic function, one had electrocardiographic abnormalities without hypertrophy, and one had the disease-causing mutation but did not fulfill the clinical criteria for the disease. The mean maximum wall thickness was 14.1 ± 6.0 mm. The three patients with dilated cardiomyopathy-like features had progressive left ventricular dilation. Three individuals underwent right ventricular endomyocardial biopsy. There was a modest degree of myocardial hypertrophy (myocyte diameter: 18.9 ± 5.2 m,m), and minimal myocardial disarray and mild fibrosis were noted. Conclusion: The Arg92Trp substitution in the cardiac troponin T gene shows a high degree of penetrance, moderate hypertrophy, and early progression to dilated cardiomyopathy in Japanese patients. Early identification of individuals with this mutation may provide the opportunity to evaluate the efficacy of early therapeutic interventions. [source]


Zebrafish as a model for long QT syndrome: the evidence and the means of manipulating zebrafish gene expression

ACTA PHYSIOLOGICA, Issue 3 2010
I. U. S. Leong
Abstract Congenital long QT syndrome (LQT) is a group of cardiac disorders associated with the dysfunction of cardiac ion channels. It is characterized by prolongation of the QT-interval, episodes of syncope and even sudden death. Individuals may remain asymptomatic for most of their lives while others present with severe symptoms. This heterogeneity in phenotype makes diagnosis difficult with a greater emphasis on more targeted therapy. As a means of understanding the molecular mechanisms underlying LQT syndrome, evaluating the effect of modifier genes on disease severity as well as to test new therapies, the development of model systems remains an important research tool. Mice have predominantly been the animal model of choice for cardiac arrhythmia research, but there have been varying degrees of success in recapitulating the human symptoms; the mouse cardiac action potential (AP) and surface electrocardiograms exhibit major differences from those of the human heart. Against this background, the zebrafish is an emerging vertebrate disease modelling species that offers advantages in analysing LQT syndrome, not least because its cardiac AP much more closely resembles that of the human. This article highlights the use and potential of this species in LQT syndrome modelling, and as a platform for the in vivo assessment of putative disease-causing mutations in LQT genes, and of therapeutic interventions. [source]


Clinical picture of EPM1-Unverricht-Lundborg disease

EPILEPSIA, Issue 4 2008
Reetta Kälviäinen
Summary Unverricht-Lundborg disease (ULD), progressive myoclonic epilepsy type 1 (EPM1, OMIM254800), is an autosomal recessively inherited neurodegenerative disorder characterized by age of onset from 6 to 16 years, stimulus-sensitive myoclonus, and tonic,clonic epileptic seizures. Some years after the onset ataxia, incoordination, intentional tremor, and dysarthria develop. Individuals with EPM1 are mentally alert but show emotional lability, depression, and mild decline in intellectual performance over time. The diagnosis of EPM1 can be confirmed by identifying disease-causing mutations in a cysteine protease inhibitor cystatin B (CSTB) gene. Symptomatic pharmacologic and rehabilitative management, including psychosocial support, are the mainstay of EPM1 patients' care. Valproic acid, the first drug of choice, diminishes myoclonus and the frequency of generalized seizures. Clonazepam and high-dose piracetam are used to treat myoclonus, whereas levetiracetam seems to be effective for both myoclonus and generalized seizures. There are a number of agents that aggravate clinical course of EPM1 such as phenytoin aggravating the associated neurologic symptoms or even accelerating cerebellar degeneration. Sodium channel blockers (carbamazepine, oxcarbazepine) and GABAergic drugs (tiagabine, vigabatrin) as well as gabapentin and pregabalin may aggravate myoclonus and myoclonic seizures. EPM1 patients need lifelong clinical follow-up, including evaluation of the drug-treatment and comprehensive rehabilitation. [source]


A clinical and genetic study of 56 Saudi Wilson disease patients: identification of Saudi-specific mutations

EUROPEAN JOURNAL OF NEUROLOGY, Issue 2 2004
M. Al Jumah
Wilson disease (WD) is a hereditary disorder, with recessive transmission and genetic heterogeneity. Several mutations of ATP7B, the gene underlying WD, were reported in many ethnic groups. In this study, mutation screening in ATP7B of 56 Saudi Arabian WD patients was undertaken. The clinical data of all patients were recorded. The entire ATP7B coding sequence, including intron,exon boundaries were screened for mutation by the polymerase chain reaction (PCR)-based mutation detection technique and DNA sequencing. Thirty-nine patients were symptomatic at presentation and 17 subjects were pre-symptomatic siblings of affected patients. Fourteen patients had neurological, 11 patients had mixed (hepatic and neurological), and 14 patients had hepatic presentations. Family history suggestive of WD was present in 72% of cases and 68% had consanguineous parents. Genetic analysis showed disease-causing mutations in three exons (exons 8, 19 and 21) of the ATP7B gene in 28 patients (50%). Mutations in exons 21 (18 cases) and 19 (one case) were unique for Saudis. This large series of Saudi patients with WD has shown wide variability in the genomic substrate of WD. There is no correlation between genotype and clinical presentation. [source]


Effect of the disease-causing mutations identified in human ribonuclease (RNase) H2 on the activities and stabilities of yeast RNase H2 and archaeal RNase HII

FEBS JOURNAL, Issue 19 2008
Muhammad S. Rohman
Eukaryotic ribonuclease (RNase) H2 consists of one catalytic and two accessory subunits. Several single mutations in any one of these subunits of human RNase H2 cause Aicardi,Goutières syndrome. To examine whether these mutations affect the complex stability and activity of RNase H2, three mutant proteins of His-tagged Saccharomyces cerevisiae RNase H2 (Sc-RNase H2*) were constructed. Sc-G42S*, Sc-L52R*, and Sc-K46W* contain single mutations in Sc-Rnh2Ap*, Sc-Rnh2Bp*, and Sc-Rnh2Cp*, respectively. The genes encoding the three subunits were coexpressed in Escherichia coli, and Sc-RNase H2* and its derivatives were purified in a heterotrimeric form. All of these mutant proteins exhibited enzymatic activity. However, only the enzymatic activity of Sc-G42S* was greatly reduced compared to that of the wild-type protein. Gly42 is conserved as Gly10 in Thermococcus kodakareansis RNase HII. To analyze the role of this residue, four mutant proteins, Tk-G10S, Tk-G10A, Tk-G10L, and Tk-G10P, were constructed. All mutant proteins were less stable than the wild-type protein by 2.9,7.6 °C in Tm. A comparison of their enzymatic activities, substrate binding affinities, and CD spectra suggests that the introduction of a bulky side chain into this position induces a local conformational change, which is unfavorable for both activity and substrate binding. These results indicate that Gly10 is required to make the protein fully active and stable. [source]


Intronic variants in BRCA1 and BRCA2 that affect RNA splicing can be reliably selected by splice-site prediction programs,

HUMAN MUTATION, Issue 1 2009
Maaike P.G. Vreeswijk
Abstract A large number of sequence variants identified in BRCA1 and BRCA2 cannot be distinguished as either disease-causing mutations or neutral variants. These so-called unclassified variants (UVs) include variants that are located in the intronic sequences of BRCA1 and BRCA2. The purpose of this study was to assess the use of splice-site prediction programs (SSPPs) to select intronic variants in BRCA1 and BRCA2 that are likely to affect RNA splicing. We performed in vitro molecular characterization of RNA of six intronic variants in BRCA1 and BRCA2. In four cases (BRCA1, c.81,6T>A and c.4986+5G>T; BRCA2, c.7617+2T>G and c.8754+5G>A) a deleterious effect on RNA splicing was seen, whereas the c.135-15_-12del variant in BRCA1 showed no effect on RNA splicing. In the case of the BRCA2 c.68,7T>A variant, RNA analysis was not sufficient to establish the clinical significance. Six SSPPs were used to predict whether an effect on RNA splicing was expected for these six variants as well as for 23 intronic variants in BRCA1 for which the effect on RNA splicing has been published. Out of a total of 174 predictions, 161 (93%) were informative (i.e., the wild-type splice-site was recognized). No false-negative predictions were observed; an effect on RNA splicing was always predicted by these programs. In four cases (2.5%) a false-positive prediction was observed. For DNA diagnostic laboratories, these programs are therefore very useful to select intronic variants that are likely to affect RNA splicing for further analysis. Hum Mutat 0,1,8, 2008. © 2008 Wiley-Liss, Inc. [source]


Detection of single nucleotide substitution by competitive allele-specific short oligonucleotide hybridization (CASSOH) with immunochromatographic strip,

HUMAN MUTATION, Issue 2 2003
Yoichi Matsubara
Abstract Recent advances in human genome research have revealed that genetic polymorphisms, such as single nucleotide polymorphisms (SNPs), are closely associated with susceptibility to various common diseases and adverse drug reactions. Also, numerous mutations responsible for a number of genetic diseases have been identified. Clinical application of genetic information to individual health care requires simple and rapid identification of nucleotide changes in clinical settings. We have devised a novel low-tech method for the detection of a single nucleotide substitution using competitive allele-specific short oligonucleotide hybridization with immunochromatographic strip. The gene of interest is PCR-amplified, hybridized to an allele-specific short oligonucleotide probe in the presence of a competitive oligonucleotide, and subjected to chromatography using a DNA test strip at room temperature. The genotype is unambiguously determined by the presence or the absence of visible purple lines on a strip. Feasibility of the method was demonstrated by the detection of a prevalent disease-causing mutations in glycogen storage disease type Ia (G6PC), medium-chain acyl-CoA dehydrogenase deficiency (ACADM), non-ketotic hyperglycinemia (GLDC), and clinically important polymorphisms in the CYP2C19 gene and the aldehyde dehydrogenase 2 gene (ALDH2). The procedure does not demand either technical expertise or expensive instruments and is readily performed in local clinical laboratories. The result is obtained within 10 min after PCR. This rapid and simple method of SNP detection may be used for point-of-care genetic diagnosis with potentially diverse clinical applications. Hum Mutat 22:166,172, 2003. © 2003 Wiley-Liss, Inc. [source]


Ten novel mutations in the human neurofibromatosis type 1 (NF1) gene in Italian patients

HUMAN MUTATION, Issue 1 2002
Paola Origone
Abstract The entire NF1 coding region was analyzed for mutations in a panel of 108 unrelated Italian NF1 patients. Using PTT, SSCP, and DNA sequencing, we found 10 mutations which have never been reported before. Clinical diagnosis of NF1 was established according to the NIH consensus criteria in 100 individuals, while 8 were young children with only multiple cafè-au-lait spots. We detected 46 truncated fragments, and 24 of them were fully characterized by SSCP and direct sequencing. Of the 24, 14 were known mutations (R304X, R681X, Q682X, R1306X, R1362X, R1513X, R1748X, Q1794X, R1947X, Y2264X, R2237X, 2674delA, 6789delTTAC, 2027insC). The other 10 mutations represent novel changes that contribute to the germline mutational spectrum of the NF1 gene (K810X, Q2595X, 6772delT, 7190delCT, 7331delA, 1021insTT, 3921insT, 4106insTA, 7149insC, 2033insCG / 2034delA). PTT in a large number of Italian NF1 patients supports the usefulness of this method for characterization of mutations in disorders where the responsible gene is very large and the disease-causing mutations often create a stop codon. In agreement with previous reports, no mutational hotspots within the NF1 gene were detected. © 2002 Wiley-Liss, Inc. [source]


Mutation analysis in mitochondrial fatty acid oxidation defects: Exemplified by acyl-CoA dehydrogenase deficiencies, with special focus on genotype,phenotype relationship

HUMAN MUTATION, Issue 3 2001
Niels Gregersen
Abstract Mutation analysis of metabolic disorders, such as the fatty acid oxidation defects, offers an additional, and often superior, tool for specific diagnosis compared to traditional enzymatic assays. With the advancement of the structural part of the Human Genome Project and the creation of mutation databases, procedures for convenient and reliable genetic analyses are being developed. The most straightforward application of mutation analysis is to specific diagnoses in suspected patients, particularly in the context of family studies and for prenatal/preimplantation analysis. In addition, from these practical uses emerges the possibility to study genotype,phenotype relationships and investigate the molecular pathogenesis resulting from specific mutations or groups of mutations. In the present review we summarize current knowledge regarding genotype,phenotype relationships in three disorders of mitochondrial fatty acid oxidation: very-long chain acyl-CoA dehydrogenase (VLCAD, also ACADVL), medium-chain acyl-CoA dehydrogenase (MCAD, also ACADM), and short-chain acyl-CoA dehydrogenase (SCAD, also ACADS) deficiencies. On the basis of this knowledge we discuss current understanding of the structural implications of mutation type, as well as the modulating effect of the mitochondrial protein quality control systems, composed of molecular chaperones and intracellular proteases. We propose that the unraveling of the genetic and cellular determinants of the modulating effects of protein quality control systems may help to assess the balance between genetic and environmental factors in the clinical expression of a given mutation. The realization that the effect of the monogene, such as disease-causing mutations in the VLCAD, MCAD, and SCAD genes, may be modified by variations in other genes presages the need for profile analyses of additional genetic variations. The rapid development of mutation detection systems, such as the chip technologies, makes such profile analyses feasible. However, it remains to be seen to what extent mutation analysis will be used for diagnosis of fatty acid oxidation defects and other metabolic disorders. Hum Mutat 18:169,189, 2001. © 2001 Wiley-Liss, Inc. [source]


Diversity of Glanzmann thrombasthenia in southern India: 10 novel mutations identified among 15 unrelated patients

JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2006
E. J. R. NELSON
Summary.,Background: Glanzmann thrombasthenia (GT) is a congenital bleeding disorder caused by either a lack or dysfunction of the platelet integrin ,IIb,3. Objectives: To determine the molecular basis of GT in patients from southern India. Patients: Fifteen unrelated patients whose diagnosis was consistent with GT were evaluated. Results: Platelet surface expression of ,IIb,3 was < 10%, 10%,50%, and > 50% of controls in five, nine, and one patient(s), respectively. Immunoblotting of the platelet lysates showed no ,IIb in 14 patients, and no ,3 in 10 patients, although severely reduced in four patients. Platelet fibrinogen was undetectable in 13 patients, and severely reduced in one patient. One patient showed normal surface ,IIb,3 expression, and normal ,IIb, ,3 and fibrinogen levels in the lysate. Ten novel candidate disease-causing mutations were identified in 11 patients. The missense mutations included Gly128Ser, Ser287Leu, Gly357Ser, Arg520Trp, Leu799Arg in ,IIb, and Cys575Gly in ,3. We have already shown that Gly128Ser, Ser287Leu, and Gly357Ser mutations variably affect ,IIb,3 surface expression. The Cys575Gly mutation may disrupt the disulphide link with Cys586 to cause the GT phenotype. The molecular pathology of the other missense mutations is not clear. Two nonsense mutations, Trp-16Stop and Glu715Stop in ,IIb, and a 7-bp deletion (330-336TCCCCAG) in ,3 are predicted to result in truncated proteins. An IVS15(,1)G , A mutation in ,IIb induced a cryptic splice site as confirmed by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Thirteen polymorphisms were also identified (five in ,IIb and eight in ,3), among which five were novel. Conclusions: While identifying a significant number of novel mutations causing GT, this study confirms the genetic heterogeneity of the disorder in southern India. [source]


Modifier genes in cystic fibrosis

PEDIATRIC PULMONOLOGY, Issue 5 2005
J.C. Davies MD
Abstract Although over 1,000 disease-causing mutations in the CFTR gene have been described, the highly variable disease phenotype in cystic fibrosis (CF) cannot be explained on the basis of this gene alone. Both the environment and other non-CFTR genes are likely to be important. The increased understanding of pathophysiological processes in the CF lung has led to several studies on genes in these pathways, including those involved in host defense, mucin production, and airway responsiveness. Additionally, candidate modifiers of the gastrointestinal manifestations of CF have been explored. One of the major aims of such studies is to produce targets for novel drug developments. This review will summarize the field to date and discuss some of the methodological issues important in the design and interpretation of such studies. Pediatr Pulmonol. © 2005 Wiley-Liss, Inc. [source]


Three novel and six common mutations in 11 patients with methylmalonic acidemia

PEDIATRICS INTERNATIONAL, Issue 1 2006
AZUSA KOBAYASHI
Abstract Background: Patients with a defect in methylmalonyl-coenzyme A mutase (MCM) are classified as having methylmalonic acidemia, which is divided into two subclasses: mut0 and mut,. Fifty-five disease-causing mutations have been identified. Although most are private mutations, only three (E117X, G717V, and N219Y) are reportedly common in Japanese, Black, and Caucasian populations, respectively. Here we identified mutations in 11 Japanese patients with MCM deficiency. Methods: Mutational analysis was performed in 11 unrelated Japanese patients with MCM deficiency using polymerase chain reaction and direct sequencing. Results: Three novel (L494X, R727X, and 449_461del) and six previously reported (R93H, E117X, N219Y, R369H, G648D and IVS2 + 5G>A) mutations were identified. The L494X mutation was found in three unrelated patients, and the R93H, E117X, R369H, G648D, and IVS2 + 5G>A mutations occurred more than once. Two of the patients were classified as mut, phenotype because of residual [14C]-propionate incorporation in the presence of a high concentration of hydroxocobalamin. The two mut, patients were heterozygous for the G648D mutation and presented with lethargy and metabolic acidosis after 2 years of life. Their psychomotor development has been documented as normal. The patients with the R727X or 449_461del mutations clinically exhibited mut0 phenotype. Two patients with mut0 phenotype died in infancy. One presented early in the neonatal period; the other was symptomatic in the late infantile period. Conclusions: The L494X, R93H, E117X, R369H, G648D, and IVS2 + 5G>A mutations are found in more than two unrelated families in the Japanese population. The short-term outcome was generally poor in patients with mut0, and therefore alternative treatments should be considered. [source]


A somatic NLRP3 mutation as a cause of a sporadic case of chronic infantile neurologic, cutaneous, articular syndrome/neonatal-onset multisystem inflammatory disease: Novel evidence of the role of low-level mosaicism as the pathophysiologic mechanism underlying mendelian inherited diseases

ARTHRITIS & RHEUMATISM, Issue 4 2010
Juan I. Aróstegui
Objective Chronic infantile neurologic, cutaneous, articular syndrome (CINCA), also known as neonatal-onset multisystem inflammatory disease (NOMID), is a severe, early-onset autoinflammatory disease characterized by an urticaria-like rash, arthritis/arthropathy, variable neurologic involvement, and dysmorphic features, which usually respond to interleukin-1 blockade. CINCA/NOMID has been associated with dominant Mendelian inherited NLRP3 mutations. However, conventional sequencing analyses detect true disease-causing mutations in only ,55,60% of patients, which suggests the presence of genetic heterogeneity. We undertook the current study to assess the presence of somatic, nongermline NLRP3 mutations in a sporadic case of CINCA/NOMID. Methods Clinical data, laboratory results, and information on treatment outcomes were gathered through direct interviews. Exhaustive genetic studies, including Sanger method sequencing, subcloning, restriction fragment length polymorphism assay, and pyrosequencing, were performed. Results The patient's CINCA/NOMID was diagnosed based on clinical features (early onset of the disease, urticaria-like rash, knee arthropathy, and dysmorphic features). The patient has exhibited a successful response to anakinra within the last 28 months. Analysis of NLRP3 identified a novel heterozygous variant (p.D303H) that was detected in ,30,38% of circulating leukocytes. The absence of this variant in healthy controls and in the patient's parents suggested a de novo true disease-causing mutation. Additional analyses showed that this novel mutation was present in both leukocyte subpopulations and epithelial cells. Conclusion Our findings identify the novel p.D303H NLRP3 variant in a Spanish patient with CINCA/NOMID as a new disease-causing mutation, which was detected as a somatic, nongermline mutation in hematopoietic and nonhematopoietic cell lineages. Our data provide new insight into the role of low-level mosaicism in NLRP3 as the pathophysiologic mechanism underlying cryopyrin-associated periodic syndrome. [source]


Structures of alternatively spliced isoforms of human ketohexokinase

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2009
Chi H. Trinh
A molecular understanding of the unique aspects of dietary fructose metabolism may be the key to understanding and controlling the current epidemic of fructose-related obesity, diabetes and related adverse metabolic states in Western populations. Fructose catabolism is initiated by its phosphorylation to fructose 1-phosphate, which is performed by ketohexokinase (KHK). Here, the crystal structures of the two alternatively spliced isoforms of human ketohexokinase, hepatic KHK-C and the peripheral isoform KHK-A, and of the ternary complex of KHK-A with the substrate fructose and AMP-PNP are reported. The structure of the KHK-A ternary complex revealed an active site with both the substrate fructose and the ATP analogue in positions ready for phosphorylation following a reaction mechanism similar to that of the pfkB family of carbohydrate kinases. Hepatic KHK deficiency causes the benign disorder essential fructosuria. The effects of the disease-causing mutations (Gly40Arg and Ala43Thr) have been modelled in the context of the KHK structure. [source]


The structure of the FERM domain of merlin, the neurofibromatosis type 2 gene product

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2002
Beom Sik Kang
Neurofibromatosis type 2 is an autosomal dominant disorder characterized by central nervous system tumors. The cause of the disease has been traced to mutations in the gene coding for a protein that is alternately called merlin or schwannomin and is a member of the ERM family (ezrin, radixin and moesin). The ERM proteins link the cytoskeleton to the cell membrane either directly through integral membrane proteins or indirectly through membrane-associated proteins. In this paper, the expression, purification, crystallization and crystal structure of the N-terminal domain of merlin are described. The crystals exhibit the symmetry of space group P212121, with two molecules in the asymmetric unit. The recorded diffraction pattern extends to 1.8,Å resolution. The structure was solved by the molecular-replacement method and the model was refined to a conventional R value of 19.3% (Rfree = 22.7%). The N-terminal domain of merlin closely resembles those described for the corresponding domains in moesin and radixin and exhibits a cloverleaf architecture with three distinct subdomains. The structure allows a better rationalization of the impact of selected disease-causing mutations on the integrity of the protein. [source]


Novel MEN1 germline mutations in Brazilian families with multiple endocrine neoplasia type 1

CLINICAL ENDOCRINOLOGY, Issue 3 2007
Rodrigo A. Toledo
Summary Objective, To characterize clinical features and identify MEN1 germline mutations in Brazilian families with multiple endocrine neoplasia type 1 (MEN1). Settings, Non-profit academic centre. Patients, Fourteen Brazilian families with MEN1 and 141 at-risk relatives. Results, We identified 12 different MEN1 disease-causing mutations, seven of them previously unreported: 308delC; 375del21; 549A>T (I147F); 1243delA; 1348T>G (L413R); 1351T>C (L414P) and 1523G>T (W471C). Families with the recurrent mutations 360delTCTA and L413R were shown to be unrelated by mitochondrial-DNA and Y-chromosome haplotype analyses. Most of the MEN1 single point mutations involved evolutionarily conserved residues, whereas most of the deletion/frameshift changes occurred in GC-rich repetitive regions. Genetic screening of 141 at-risk family members identified 38 MEN1 mutation carriers, 37 (97·4%) of whom had at least one major MEN1-related tumour upon clinical investigation. Conclusions, High frequencies of MEN1 gene mutations were detected in Brazilian families with MEN1, including seven new genetic mutations that are predicted to cause inactivation of the MEN1 tumour suppressor gene. Our data underscore the need to implement a systematic MEN1 screening programme in Brazil. [source]


Novel polymorphisms and lack of mutations in the ACD gene in patients with ACTH resistance syndromes

CLINICAL ENDOCRINOLOGY, Issue 2 2007
Catherine E. Keegan
Summary Objective ACTH resistance is a feature of several human syndromes with known genetic causes, including familial glucocorticoid deficiency (types 1 and 2) and triple A syndrome. However, many patients with ACTH resistance lack an identifiable genetic aetiology. The human homolog of the Acd gene, mutated in a mouse model of adrenal insufficiency, was sequenced in 25 patients with a clinical diagnosis of familial glucocorticoid deficiency or triple A syndrome. Design A 3·4 kilobase genomic fragment containing the entire ACD gene was analysed for mutations in all 25 patients. Setting Samples were obtained by three investigators from different institutions. Patients The primary cohort consisted of 25 unrelated patients, primarily of European or Middle Eastern descent, with a clinical diagnosis of either familial glucocorticoid deficiency (FGD) or triple A syndrome. Patients lacked mutations in other genes known to cause ACTH resistance, including AAAS for patients diagnosed with triple A syndrome and MC2R and MRAP for patients diagnosed with familial glucocorticoid deficiency. Thirty-five additional patients with adrenal disease phenotypes were added to form an expanded cohort of 60 patients. Measurements Identification of DNA sequence changes in the ACD gene in the primary cohort and analysis of putative ACD haplotypes in the expanded cohort. Results No disease-causing mutations were found, but several novel single nucleotide polymorphisms (SNPs) and two putative haplotypes were identified. The overall frequency of SNPs in ACD is low compared to other gene families. Conclusions No mutations were identified in ACD in this collection of patients with ACTH resistance phenotypes. However, the newly identified SNPs in ACD should be more closely examined for possible links to disease. [source]


Molecular and phenotypic characteristics of patients with phenylketonuria in Serbia and Montenegro

CLINICAL GENETICS, Issue 2 2006
M Stojiljkovic
Phenylketonuria (PKU) is the most common inborn error of amino acid metabolism in Caucasians. PKU is caused by mutations in the gene encoding phenylalanine hydroxylase (PAH) enzyme. Here, we report the spectrum and the frequency of mutations in the PAH gene and discuss genotype,phenotype correlation in 34 unrelated patients with PKU from Serbia and Montenegro. Using both polymerase chain reaction,restriction fragment length polymorphism and ,broad-range' denaturing-gradient gel electrophoresis/DNA sequencing analysis, 19 disease-causing mutations were identified, corresponding to mutation detection rate of 97%. The most frequent ones were L48S (21%), R408W (18%), P281L (9%), E390G (7%) and R261Q (6%), accounting for 60% of all mutant alleles. The genotype,phenotype correlation was studied in homozygous and functionally hemizygous patients. We found that the most frequent mutation, L48S, was exclusively associated with the classical (severe) PKU phenotype. The mutation E390G gave rise to mild PKU. For the mutation R261Q, patients had been recorded in two phenotype categories. Considering allele frequencies, PKU in Serbia and Montenegro is heterogeneous, reflecting numerous migrations over the Balkan Peninsula. [source]


A genetic model for determining MSH2 and MLH1 carrier probabilities based on family history and tumor microsatellite instability

CLINICAL GENETICS, Issue 3 2006
F Marroni
Mutation-predicting models can be useful when deciding on the genetic testing of individuals at risk and in determining the cost effectiveness of screening strategies at the population level. The aim of this study was to evaluate the performance of a newly developed genetic model that incorporates tumor microsatellite instability (MSI) information, called the AIFEG model, and in predicting the presence of mutations in MSH2 and MLH1 in probands with suspected hereditary non-polyposis colorectal cancer. The AIFEG model is based on published estimates of mutation frequencies and cancer penetrances in carriers and non-carriers and employs the program MLINK of the FASTLINK package to calculate the proband's carrier probability. Model performance is evaluated in a series of 219 families screened for mutations in both MSH2 and MLH1, in which 68 disease-causing mutations were identified. Predictions are first obtained using family history only and then converted into posterior probabilities using information on MSI. This improves predictions substantially. Using a probability threshold of 10% for mutation analysis, the AIFEG model applied to our series has 100% sensitivity and 71% specificity. [source]


DNA sequence analysis for structure/function and mutation studies in Becker muscular dystrophy

CLINICAL GENETICS, Issue 1 2005
SA Hamed
We systematically screened the whole coding region of 18 male muscular dystrophy patients whose clinical, histological and laboratory findings suggest Becker muscular dystrophy (present but abnormal dystrophin). No systematic mutation study of a cohort of patients with dystrophin of normal quality but abnormal quantity has been published. The complete coding sequence of the dystrophin gene (11 kb) of each patient was subjected to an automated sequence analysis by using muscle biopsy RNA; 535 bp of the gene promoter and 5,UTR were likewise sequenced. We identified seven disease-causing mutations (40%). Six were novel, including missense, nonsense, small deletion and splice site mutations. Sixty percent (11/18) of patients with decreased quantities of normal molecular weight dystrophin showed no mutation, but most of them had a family history highly suggestive of X-linked inheritance, suggesting transcription or translational deleterious affection, i.e. outside what was screened. Quantitative multiplex fluorescence polymerase chain studies of mutation-negative patients showed normal levels of dystrophin mRNA. In three patients, there was some reduction of the transcript suggesting a deleterious undetected gene change resulted in the reduction of RNA levels. Our data address important structure/function and genotype/phenotype correlations and it suggests that dystrophin protein studies must be interpreted with caution in deletion-negative male muscular dystrophy patients. [source]