Carrier detection by microsatellite analysis of Duchenne/Becker muscular dystrophy in Hungarian families

Intragenic DNA polymorphism analysis of DMD/BMD dystrophy gene for carrier and prenatal diagnosis in 60 Iranian healthy individuals

Duchenne and Becker muscular dystrophies (DMD/BMD) are allelic, x-linked neuromuscular disease resulting from mutations in dystrophin gene. DMD is the most severe and frequent inherited but still incurable disease in males. About two-third of such patients have large deletions or duplications that can be identified by multiplex polymerase chain reaction (PCR). In one-third of remaining cases, a linkage analysis that involves DNA markers of intragenic dystrophic gene is considered a rapid and simple method for carrier detection and prenatal diagnosis. In the present study, we investigated frequency and heterozygosity of three polymorphic restriction sites and also four highly polymorphic (CA)(n) repeat microsatellites loci within hot spots region of human dystrophin gene in 60 healthy Iranian populations. Our findings indicated that the allele frequencies of pERT87-8/TaqI, pERT87-15/BamHI, and pERT87-15/XmnI were 0.23/0.77, 0.221/0.779, and 0.239/0.761, respectively. Among these three polymorphic sites, pERT78-15/XmnI locus had the highest heterozygosity with frequency of 47.17%. We also found that STR49 had the highest heterozygosity among four polymorphic microsatellites. These findings are useful in linkage analysis of Iranian DMD families in both carrier detection and prenatal diagnosis.

X-linked recessive Menkes disease: identification of partial gene deletions in affected males

Menkes disease is an X-linked recessive lethal disorder of copper metabolism, caused by defects in the ATP7A gene. Partial gene deletions comprise about 15% of the mutations causing Menkes disease. We have previously demonstrated identification of partial ATP7A deletions in patients by Southern blot analysis. In the present study, we report the use of three fast and reliable polymerase chain reaction (PCR)-based methods for the identification of partial ATP7A deletions in Menkes disease patients. First we demonstrate the use of multiplex PCR, a fast method for identification and rough localization of partial gene deletions, in which two exons of ATP7A are coamplified. Second, we present PCR amplification of genomic DNA across the deletion junctions, a method enabling identification of the deletion breakpoints and hence the exact size of the deletion. Finally, application of reverse transcription PCR (RT-PCR) for identification and localization of gene deletions at the cDNA level is demonstrated. By studying the mutation at the cDNA level the predicted effect of the mutation on the amino acid sequence and consequently the protein structure and function can be inferred. We demonstrate characterization of partial gene deletions in five patients, and in three of these we were able to determine the breakpoint sequences.