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Molecular Causes (molecular + cause)
Selected AbstractsPituitary Transcription Factors: From Congenital Deficiencies to Gene TherapyJOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2006M. H. Quentien Despite the existence of interspecies phenotypic variability, animal models have yielded valuable insights into human pituitary diseases. Studies on Snell and Jackson mice known to have growth hormone, prolactin and thyroid-stimulating hormone deficiencies involving the hypoplastic pituitary gland have led to identifying alterations of the pituitary specific POU homeodomain Pit-1 transcription factor gene. The human phenotype associated with rare mutations in this gene was found to be similar to that of these mice mutants. Terminal differentiation of lactotroph cells and direct regulation of the prolactin gene both require interactions between Pit-1 and cell type specific partners, including panpituitary transcriptional regulators such as Pitx1 and Pitx2. Synergistic activation of the prolactin promoter by Pitx factors and Pit-1 is involved not only in basal condition, but also in responsiveness to forskolin, thyrotrophin-releasing-hormone and epidermal growth factor. In corticotroph cells, Pitx1 interacts with Tpit. Tpit mutations have turned out to be the main molecular cause of neonatal isolated adrenocorticotrophin deficiency. This finding supports the idea that Tpit plays an essential role in the differentiation of the pro-opiomelanocortin pituitary lineage. The effects of Pit-1 are not restricted to hormone gene regulation because this factor also contributes to cell division and protects the cell from programmed cell death. Lentiviral vectors expressing a Pit-1 dominant negative mutant induced time- and dose-dependent cell death in somatotroph and lactotroph adenomas in vitro. Gene transfer by lentiviral vectors should provide a promising step towards developing an efficient specific therapeutic approach by which a gene therapy programme for treating human pituitary adenomas could be based. [source] Diagnosis, clinical features and molecular assessment of the dysfibrinogenaemiasHAEMOPHILIA, Issue 5 2008M. HILL Summary., Hereditary dysfibrinogenaemia is characterized by the presence of functionally abnormal plasma fibrinogen. Dysfibrinogenaemia is a heterogeneous disorder associated with different mutations throughout the three genes that code for the fibrinogen sub-units, affecting many different aspects of fibrinogen/fibrin activity. Dysfibrinogenaemia may be discovered during the investigation of individuals who present with bleeding or thombosis, or may be found in individuals during routine coagulation screening. More specialized coagulation tests may confirm the diagnosis of dysfibrinogenaemia but do not reliably distinguish between the different fibrinogen variants and are not usually useful in predicting bleeding or thrombotic risk. Advances in molecular diagnostics have facilitated the investigation of the molecular causes of fibrinogen disorders. Several ,hot spot' areas have been identified where mutations causing a high proportion of cases of dysfibrinogenaemia are found (A,Arg16 and ,Arg275). Molecular diagnostics have also shown that many fibrinogen variants share the same causative mutation. There is a discrepancy between the quality of the molecular and functional data available for each mutation and the clinical information on individuals and their family members. However, there are accumulating data that the ,hot spot' mutations accounting for 60,80% of cases of dysfibringenaemia are not associated with a significant bleeding or thrombosis in the absence of other risk factors. Rapid screening for these mutations may provide reassurance for patients in the presurgical setting. [source] p.Gln200Glu, a putative constitutively active mutant of rod ,-transducin (GNAT1) in autosomal dominant congenital stationary night blindness,,HUMAN MUTATION, Issue 7 2007Viktoria Szabo Abstract Congenital stationary night blindness (CSNB) is a non-progressive Mendelian condition resulting from a functional defect in rod photoreceptors. A small number of unique missense mutations in the genes encoding various members of the rod phototransduction cascade, e.g. rhodopsin (RHO), cGMP phosphodiesterase ,-subunit (PDE6B), and transducin ,-subunit (GNAT1) have been reported to cause autosomal dominant (ad) CSNB. While the RHO and PDE6B mutations result in constitutively active proteins, the only known adCSNB-associa-ted GNAT1 change (p.Gly38Asp) produces an ,-transducin that is unable to activate its downstream effector molecule in vitro. In a multigeneration Danish family with adCSNB, we identified a novel heterozygous C to G transversion (c.598C>G) in exon 6 of GNAT1 that should result in a p.Gln200Glu substitution in the evolutionarily highly conserved Switch 2 region of ,-transducin, a domain that has an important role in binding and hydrolyzing GTP. Computer modeling based on the known crystal structure of transducin suggests that the p.Gln200Glu mutant exhibits impaired GTPase activity, and thereby leads to constitutive activation of phototransduction. This assumption is in line with our results of trypsin protection assays as well as previously published biochemical data on mutants of this glutamine in the GTPase active site of ,-transducin following in vitro expression, and observations that inappropriately activating mutants of various members of the rod phototransduction cascade represent one of the major molecular causes of adCSNB. © 2007 Wiley-Liss, Inc. [source] Cell death mechanisms in neurodegenerationJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 1 2001K. A. Jellinger Abstract Progressive cell loss in specific neuronal populations often associated with typical cytoskeletal protein aggregations is a pathological hallmark of neurodegenerative disorders, but the nature, time course and molecular causes of cell death and their relation to cytoskeletal pathologies are still unresolved. Apoptosis or alternative pathways of cell death have been discussed in Alzheimer's disease and other neurodegenerative disorders. Apoptotic DNA fragmentation in human brain as a sign of neuronal injury is found too frequent as to account for continous neuron loss in these slowly progressive processes. Morphological studies revealed extremely rare apoptotic neuronal death in Alzheimer's disease but yielded mixed results for Parkinson's disease and other neurodegenerative disorders. Based on recent data in human brain, as well as in animal and cell culture models, a picture is beginning to emerge suggesting that, in addition to apoptosis, other forms of programmed cell death may participate in neurodegeneration. Better understanding of the molecular players will further elucidate the mechanisms of cell death in these disorders and their relations to cytoskeletal abnormalities. Susceptible cell populations in a proapoptotic environment show increased vulnerability towards multiple noxious factors discussed in the pathogenesis of neurodegeneration. In conclusion, although many in vivo and in vitro data are in favor of apoptosis involvement in neurodegenerative processes, there is considerable evidence that very complex events may contribute to neuronal death with possible repair mechanisms, the elucidation of which may prove useful for future prevention and therapy of neurodegenerative disorders. [source] Syndromic craniosynostosis: from history to hydrogen bondsORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 2 2007ML Cunningham Structured Abstract Authors,,, Cunningham ML, Seto ML, Ratisoontorn C, Heike CL, Hing AV The syndromic craniosynostoses, usually involving multiple sutures, are hereditary forms of craniosynostosis associated with extracranial phenotypes such as limb, cardiac, CNS and tracheal malformations. The genetic etiology of syndromic craniosynostosis in humans is only partially understood. Syndromic synostosis has been found to be associated with mutations of the fibroblast growth factor receptor family (FGFR1, -R2, -R3), TWIST1, MSX2, and EFNB1. Apert, Pfeiffer, Crouzon, and Jackson-Weiss syndromes are due to gain-of-function mutations of FGFR2 in either the Ig II,III linker region (Apert) or Ig III domain. Loss of function mutations of TWIST1 and gain-of-function mutations of MSX2 lead to Saethre,Chotzen and Boston-type syndromes, respectively. The mutations in Pfeiffer (FGFR1), Muenke (FGFR3), and Apert syndrome (FGFR2) are caused by the same amino acid substitution in a highly conserved region of the Ig II,III linker region of these proteins, which suggests that these receptor tyrosine kinases have an overlapping function in suture biology. In this review we will discuss the historical descriptions, current phenotypes and molecular causes of the more common forms of syndromic craniosynostosis. [source] Developmental and degenerative features in a complicated spastic paraplegiaANNALS OF NEUROLOGY, Issue 4 2010M. Chiara Manzini PhD Objective We sought to explore the genetic and molecular causes of Troyer syndrome, one of several complicated hereditary spastic paraplegias (HSPs). Troyer syndrome had been thought to be restricted to the Amish; however, we identified 2 Omani families with HSP, short stature, dysarthria and developmental delay,core features of Troyer syndrome,and a novel mutation in the SPG20 gene, which is also mutated in the Amish. In addition, we analyzed SPG20 expression throughout development to infer how disruption of this gene might generate the constellation of developmental and degenerative Troyer syndrome phenotypes. Methods Clinical characterization of 2 non-Amish families with Troyer syndrome was followed by linkage and sequencing analysis. Quantitative polymerase chain reaction and in situ hybridization analysis of SPG20 expression were carried out in embryonic and adult human and mouse tissue. Results Two Omani families carrying a novel SPG20 mutation displayed clinical features remarkably similar to the Amish patients with Troyer syndrome. SPG20 mRNA is expressed broadly but at low relative levels in the adult brain; however, it is robustly and specifically expressed in the limbs, face, and brain during early morphogenesis. Interpretation Null mutations in SPG20 cause Troyer syndrome, a specific clinical entity with developmental and degenerative features. Maximal expression of SPG20 in the limb buds and forebrain during embryogenesis may explain the developmental origin of the skeletal and cognitive defects observed in this disorder. ANN NEUROL 2010;67:516,525 [source] The brachydactylies: a molecular disease familyCLINICAL GENETICS, Issue 2 2009S Mundlos Brachydactyly refers to shortening of the hands and/or feet due to missing, deformed, or shortened bones. It may occur as an isolated trait or as part of a syndrome. According to their pattern of skeletal involvement, the isolated brachydactyly forms have been categorized in the groups A,D including several subgroups. As in many other genetic conditions, there is considerable phenotypic overlap between the groups. The identification of the molecular causes of these conditions has offered insights into their pathogenesis. The generation of animal models has facilitated research on the pathogenic events during digit development that lead to the brachydactyly phenotype. These studies have shown that the BMP pathway plays a pivotal role in the normal development of digits and joints and that the majority of brachydactyly disease genes are directly or indirectly linked to this pathway. Together, these genes function in a regulatory network which is deregulated in the disease state. As a consequence of the close interactions within the network, overlapping phenotypes are generated that are, nevertheless, characterized by specific recognizable patterns. This principle does not only apply for the brachydactylies but is also valid for many other disease entities. Groups of diseases that show a common phenotypic pattern due to the deregulation of a molecular network are suggested to be called molecular disease families. [source] | |||||||||||||