FEASIBILITY OF SHORT TANDEM REPEATS (STR) ANALYSIS FOR CARRIER DETECTION AND PRENATAL DIAGNOSIS IN FAMILIES WITH DUCHENNE MUSCULAR DYSTROPHY (DMD)
Objective: To determine the feasibility of Short Tandem Repeats (STR) based linkage analysis for carrier detection and prenatal diagnosis (PND) in families having children affected with Duchenne Muscular Dystrophy.
Study design: Case series
Settings: Department of Chemical Pathology and Endocrinology in collaboration with Department of Molecular Biology, Armed Forces Institute of Pathology (AFIP), Rawalpindi.
Duration: From February 2007 to January 2008.
Subjects: Six unrelated families with at least one affected child in each family who had characteristic features of DMD (index case).
Materials and Methods: PCR for Duchenne Muscular Dystrophy was carried out with STR based linkage analysis at introns 44, 45, 49 and 50 of DMD gene .Thermal cycling in TC-480 (Perkin Elmer) included 25 cycles each comprising 30 sec denaturation at 94ºC, annealing at 62ºC for 30 sec, extension at 65ºC for 2 min. The final extension was done for 3 min. The amplified products were run on 8% nondenaturing polyacrylamide gel electrophoresis (PAGE) carried out at 200V for three hours on electrophoresis apparatus (Bio-Rad UK). The gels were stained in silver nitrate. By comparing STR pattern of X-chromosome allele of index case with X-chromosome alleles of the mother, the diseased or affected X-chromosome was ascertained.
Results: Carrier detection and prenatal diagnosis was feasible with STR marker at intron 44 in DMD families. It was informative in 5 out of 6 DMD families.
Conclusion: Carrier detection and PND by STR based linkage analysis is technically feasible in Pakistani families with DMD.