Carrier Detection (carrier + detection)

Distribution by Scientific Domains

Selected Abstracts

Single nucleotide polymorphisms of the factor IX gene for linkage analysis in the southern Chinese population

Vivian Chan
Carrier detection and prenatal testing for haemophilia B in Oriental populations have been hampered by the lack of informative markers within the factor IX (FIX) gene. We detected a T/C nucleotide variation at nucleotide 32770 in the poly-A region of the FIX gene in the mother of a haemophilia B child. Analysis of 139 unrelated alleles revealed a heterozygosity rate of 0193, thus offering an additional marker for linkage analysis. Together with two other polymorphic sites (5,MseI and 3,HhaI) found in Chinese and Thai populations, these polymorphisms were useful in 66% of the families studied. [source]

Carrier frequency of SMA by quantitative analysis of the SMN1 deletion in the Iranian population

M. Hasanzad
Background and purpose:, Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder. Carrier frequency studies of SMA have been reported for various populations. Although no large-scale population-based studies of SMA have been performed in Iran, previous estimates have indicated that the incidence of autosomal recessive disorder partly because of the high prevalence of consanguineous marriage is much higher in the Iranian population than in other populations. Methods:, In this study, we used a reliable and highly sensitive quantitative real-time PCR assay with SYBR green I dye to detect the copy number of the SMN1 gene to determine the carrier frequency of SMA in 200 healthy unrelated, non-consanguineous couples from different part of Iran. Results:, To validate the method in our samples, we determined the relative quantification (RQ) of patients with homozygous deletion (0.00) and hemyzygous carriers (0.29,0.55). The RQ in 10 of 200 normal individuals were within the carrier range of 0.31,0.57, estimating a carrier frequency of 5% in the Iranian population. Conclusions:, Our data show that the SMA carrier frequency in Iran is higher than in the European population and that further programs of population carrier detection and prenatal testing should be implemented. [source]

Analysis of Factor VIII polymorphic markers as a means for carrier detection in Brazilian families with haemophilia A

HAEMOPHILIA, Issue 4 2007
Summary., Haemophilia A is an X-linked, recessively inherited bleeding disorder of varying severity, which results from the deficiency of procoagulant factor VIII f(8). Linkage diagnosis using polymorphic markers in the f8 gene is widely used to detect carriers. The objective of this study was to verify the informativeness of three polymorphic markers in the Brazilian population, to evaluate the usefulness of such markers in carrier detection procedures. Sixty-three unrelated healthy volunteers and 10 haemophilic families were studied. Two microsatellite repeats and one HindIII RFLP markers were used. Carrier and non-carrier status could be determined in 80% of females investigated. Intron 13 markers presented the highest heterozygosity rate (79%) followed by intron 22 (68%) and intron 19 (57%). When all three markers were used together, linkage analysis informativeness increased significantly. We conclude that these markers are suitable for carrier detection in the Brazilian population and we recommend their use in combination to maximize diagnostic efficiency. [source]

Allelic heterogeneity of molecular events in human coagulation factor IX in Asian Indians,,

HUMAN MUTATION, Issue 5 2007
Anubha Mahajan
Abstract Mutations in Factor IX gene (F9) cause X-linked recessive bleeding disorder hemophilia B. Here, we characterized molecular events in nine North Indian hemophiliac families identifying four missense mutations (three novel), two nonsense mutations, and a deletion. We have also captured the mutational spectrum of this disease in India based on available reports and established their genotype/phenotype relationships. Indian F9 mutations data indicate the absence of an important germline mutagen in the Indian subcontinent over the last century, and are consistent with previously made conclusions that universal, presumably endogenous factors are predominant in the causation of the spontaneous mutations in F9. We also analyzed the distribution of Ala194Thr polymorphism in 1231 Asian Indians and have established that Ala variant is far more frequent and can certainly be exploited for carrier detection, contrary to earlier reports. 2007 Wiley-Liss, Inc [source]

Role of RFLP using TspRI for carrier detection in Glanzmann's thrombasthenia: a report on two families

Summary Glanzmann's thrombasthenia (GT) was diagnosed in two patients who presented with bleeding manifestations accompanied by absent platelet aggregation, secondary to adenosine-5'-diphosphate, adrenaline, arachidonic acid and collagen. Flow cytometry analysis for GPIIb/IIIa expression was done using CD61 and CD41 markers in these patients and their family members including siblings. The patients were sub typed as Type I as he had absent glycoproteins (GP) IIb/IIIa. Family studies by flow cytometry showed reduced GPII/IIIa expression in both the parents and one sibling. However, western blot showed abnormal GPIIb protein in all the family members including siblings. It is possible that abnormal GPIIb protein by western blot in family members may reflect their carrier status. Patients' DNA was analyzed for mutation in both the GPIIb and GPIIIa genes by conformational sensitive gel electrophoresis (CSGE), followed by sequencing. CSGE showed defect in exon 12 and the promoter region of GPIIb. By sequence, it was confirmed that both the mutations were homozygous one was c.1028T>C and the other one was M33320.1:g.951G>A. For one of these mutations, restriction fragment length polymorphism (RFLP) was developed to look for the same mutation in all the family members. RFLP was developed using a restriction enzyme (TspRI) against the patient's mutation, c.1028T>C in exon 12 of GPIIb gene. RFLP followed by gel electrophoresis revealed that the mutation was heterozygous in all the family members. The findings by RFLP were double confirmed by direct DNA sequencing of the exon 12 in all the family members. Thus, TspRI marker may be used as a RFLP marker to predict the carriers in GT families, if the patients' mutation status is identified. [source]

Preonset Studies of Spondyloepiphyseal Dysplasia Tarda Caused by a Novel 2-Base Pair Deletion in SEDL Encoding Sedlin,

Steven Mumm
Abstract Spondyloepiphyseal dysplasia tarda (SEDT), an X-linked recessive skeletal disorder, presents with disproportionate short stature and "barrel-chest" deformity in affected (hemizygous) adolescent boys. In four reported families to date, mutations in a gene designated SEDL (spondyloepiphyseal dysplasia late) cosegregate with SEDT. We diagnosed SEDT in a short-stature, kyphotic 15-year-old boy because of his characteristic vertebral malformations. Clinical manifestations of SEDT were evident in at least four previous generations. A novel 2-base pair (bp) deletion in exon 5 of SEDL was found in the propositus by polymerase chain reaction (PCR) amplification and sequencing of all four coding exons. The mutation ATdel241-242 cosegregated with the kindred's skeletal disease. The deletion is adjacent to a noncanonical splice site for exon 5 but does not alter splicing. Instead, it deletes 2 bp from the coding sequence, causing a frameshift. A maternal aunt and her three young sons were investigated subsequently. Radiographs showed subtle shaping abnormalities of her pelvis and knees, suggesting heterozygosity. X-rays of the spine and pelvis of her 8-year-old son revealed characteristic changes of SEDT, but her younger sons (aged 6 years and 3 years) showed no abnormalities. SEDL analysis confirmed that she and only her eldest boy had the 2-bp deletion. Molecular testing of SEDL enables carrier detection and definitive diagnosis before clinical or radiographic expression of SEDT. Although there is no specific treatment for SEDT, preexpression molecular testing of SEDL could be helpful if avoiding physical activities potentially injurious to the spine and the joints proves beneficial. [source]

,-thalassaemia carrier detection by ELISA: A simple screening strategy for developing countries

M. Shyla Ravindran
Abstract The frequency of ,-thalassaemia in India ranges from 3.5% to 15% in the general population and of the 100,000 children born with thalassaemia major in the world, 10,000 are in India alone. Affected children do not die immediately, but treatment by regular transfusion is costly and leads to iron overload and death. Therefore, health services in lower-economic countries can sustain patients only if the numbers can be limited. Detecting carrier couples by simple blood test can prevent thalassaemia and at-risk couples can be identified and informed of their genetic risk before having children. A prevention programme including population screening, counselling, and prenatal diagnosis will markedly reduce the birth prevalence of affected individuals. Hemoglobin A2 (HbA2) measurement in human hemolysates has great significance, since its level can indicate ,-thalassaemia carrier status in otherwise healthy individuals. We have developed a rapid, simple, and inexpensive enzyme linked immunosorbent assay (ELISA) for the quantitation of HbA2, which can be used in carrier screening programmes in developing countries like India. In a limited trial for ,-thalassaemia carrier screening, the results obtained with ELISAs were compared with those obtained with the microcolumn chromatography method (r=0.89). J. Clin. Lab. Anal. 19:22,25, 2005. 2005 Wiley-Liss, Inc. [source]

Parental attitudes to the identification of their infants as carriers of cystic fibrosis by newborn screening

Sharon Lewis
Aim: To investigate parental attitudes to cystic fibrosis (CF) carrier detection of their infant by newborn screening (NBS). Methods: Data were collected from a postal questionnaire sent to parents of infants identified as CF carriers by NBS in 1996,1997 (inclusive) and 2001 in Victoria, Australia (n = 66). Results: Almost all parents remembered their child being identified as a CF carrier (97%: 1996/1997; 100%: 2001); yet the majority were unaware at the time that NBS could detect carriers (70%: 1996/1997; 49%: 2001). More parents in the later cohort reported having carrier testing compared with the earlier cohort (85% and 53% respectively) but recall was more uncertain in the earlier cohort when validated against health records. Cascade testing was not utilised frequently by other family members in either cohort. Residual risk of being a carrier if testing was negative was not well understood by parents. Some parents (28%: 1996/1997; 18%: 2001) had residual anxiety about the current health of their charrier child and their future reproductive decision making. Most parents were satisfied with the information provided to them at the time of the sweat test. Few differences were seen between the cohorts. Conclusion: Although the NBS process for CF in Victoria is working efficiently for the majority of families whose infant is identified as a carrier there are areas that can be improved. We recommend that greater attention should be given to informing parents that a consequence of NBS is CF carrier detection and strategies to improve utilisation of cascade testing should be developed. [source]

A highly informative, multiplexed assay for the indirect detection of hemophilia A using five-linked microsatellites

Summary.,Background:,Hemophilia A is a severe bleeding disorder caused by almost 1000 different known mutations in the F8C gene. Direct mutation analysis is sometimes difficult for this disorder. When a mutation cannot be found, linkage analysis can be used for prenatal and carrier diagnosis. Aim:,To develop a rapid and effective system for carrier detection and prenatal diagnosis of hemophilia A based on a single-multiplexed polymerase chain reaction (PCR) reaction utilizing five microsatellite markers. Patients and methods:,Two intronic microsatellites and three other markers flanking the factor VIII gene were ascertained, and primers were designed for multiplex PCR amplification. A kindred with Hemophilia A was tested for linkage using the panel of primers, and informativity in the general population was ascertained by testing 50 unrelated females. Results:,Co-amplification of all microsatellites was optimized using DNA extracted by standard methods. Rapid detection and sizing of products were carried out using an automated DNA sequencer. The combined microsatellite panel was informative in each of the kindreds tested, and in 100% of the 50 unrelated females (95% CI 94.2,100%). Conclusions:,This method enables the indirect detection of hemophilia A for patients in whom mutations cannot be found, facilitating carrier testing and prenatal analysis. It is rapid and straightforward compared with many other published protocols, and offers a high degree of informativity. [source]

Cosegregation of a Factor VIII Microsatellite Marker with Mild Hemophilia A in Golden Retriever Dogs

Marjory B. Brooks
Mild hemophilia A (factor VIII deficiency) was diagnosed in Golden Retrievers and pedigree studies were undertaken to test the cosegregation of an intragenic factor VIII marker with the disease phenotype. The study population consisted of 30 client-owned dogs (22 males and 8 females). Hemophilic males (n = 12) typically demonstrated prolonged bleeding after trauma or surgery rather than spontaneous hemorrhagic events. The affected males had a proportionate reduction in factor VIII coagulant activity (mean FVIII:C = 4%) and factor VIII protein concentration (mean FVIII:Ag = 3%). Twenty-five dogs (10 affected males, 8 clear males, 2 obligate carrier dams, and 5 suspect carrier daughters) were genotyped for a factor VIII microsatellite marker, with allele size assigned by an automated capillary electrophoresis system. Five distinct marker alleles were present in the study pedigree and a 300-base pair allele was found to segregate with the hemophilia A phenotype. The inheritance of the hemophilia-associated allele defined carrier status for 5 suspect daughters of obligate carrier dams. The limitations inherent to linkage analyses (ie, lack of access to key family members and homozygosity at the marker locus) did not preclude carrier detection in this pedigree. We conclude that genotype analysis for the intragenic factor VIII marker can aid in control of canine hemophilia A through enhanced carrier detection. [source]

Xeroderma pigmentosum , bridging a gap between clinic and laboratory

Shin-Ichi Moriwaki
Xeroderma pigmentosum (XP) is an autosomal recessive photosensitive disorder with an extremely high incidence of UV-related skin cancers associated with impaired ability to repair UV-induced DNA damage. There are seven nucleotide excision repair (NER) complementation groups (A through G) and an NER proficient form (XP variant). XPA, B, D and G patients may also develop XP neurological disease. The laboratory diagnosis of XP can be performed by autoradiography. Recently, the isolation and characterization of the genes responsible for XP have made it possible to use molecular biological techniques to diagnose XP patients, for carrier detection and for prenatal diagnosis, especially in Japanese XPA patients. These techniques include polymerase chain reaction (PCR) and plasmid host cell reactivation assays with cloned XP genes. DNA damage is not repaired by the NER system equally throughout the genome. There are two DNA repair pathways: 1) transcription-coupled repair, and 2) global genome repair. Many factors involved in these pathways are related to the pathogenesis of XP and a related photosensitive disease, Cockayne syndrome. Clinical management consists of early diagnosis followed by a rigorous program of sun protection including avoidance of unnecessary UV exposure, wearing UV blocking clothing, and use of sunblocks on the skin. Although there is no cure for XP, the efficacy of oral retinoids for the prevention of new skin cancers, local injection of interferon, and the external use of a prokaryotic DNA repair enzyme have been reported. [source]

Prenatal diagnosis of spinal muscular atrophy: Indian scenario

Akanchha Kesari
Abstract Objectives To study the psychosocial issues associated with prenatal diagnosis of SMA in India and the use of SMN1 copy number analysis for carrier detection prior to offering prenatal diagnosis. Methods Homozygous deletion of SMN1 gene was done by PCR-RFLP. Copy number analysis of SMN1 gene was performed by quantitative PCR. Results We report our experience of eight cases of prenatal diagnosis for SMA and the use of carrier detection prior to offering prenatal diagnosis. Quantitative PCR results show that SMN1 copy number analysis is useful to identify couples at risk. Conclusion Case analyses depict unique psychosocial issues associated with prenatal diagnosis of SMA from India. Copyright 2005 John Wiley & Sons, Ltd. [source]

Heterozygote Carrier Testing in High Schools Abroad: What are the Lessons for the U.S.?

Lainie Friedman Ross M.D., Ph.D.Article first published online: 23 NOV 200
The main value of carrier detection in the general population is to determine reproductive risks. In this manuscript I examine the practice of providing carrier screening programs in the school setting. While the data show that high school screening programs can achieve high uptake, I argue that this may reflect a lack of full understanding about risks, benefits, and alternatives, and the right not to know. It may also reflect the inherent coercion in group testing, particularly for adolescents who are prone to peer pressure. The problem of carrier screening in the schools is compounded when the condition has a predilection for certain groups based on race, ethnicity or religion. I examine programs around the world that seek to test high school students for Tay Sachs and Cystic Fibrosis carrier status. I argue that carrier programs should be designed so as to minimize stigma and to allow individuals to refuse. The mandatory school environment cannot achieve this. Rather, I conclude that screening programs should be designed to attract young adults and not adolescents to participate in a more voluntary venue. [source]