[Cloning of deletion junctions: a method of PCR for detecting the deletional pseudohypertrophic muscular dystrophy carriers].

Dystrophin gene deletion junction is the unique DNA sequence resulted from illegitimate recombination after the gene deletion. A novel accurate approach is presented here for the detection of deletional pseudohypertrophic muscular dystrophy carriers with the deletion junctions.A Becker muscular dystrophy (BMD) family from Zhaoqing, Guangdong, China was used. Two males in the family were diagnosed as BMD patients, 3 phenotypically normal females and 1 chorionic villi sample of an artificial abortion were waiting for diagnosis. The index patient was identified as exons 3-5 deletion of the dystrophin gene. Then a PCR-based genome-walking method was used to locate the breakpoints in corresponding introns. Finally, deletion junctions of the 6 family members were amplified by PCR with primers adjacent to breakpoints and sequenced.The deletion junctions of all patients and carriers of the BMD family were cloned and sequenced. The 3 females and 1 chorionic tissue were diagnosed as female carriers.In this study researchers have successfully carried out accurate gene diagnosis of deletional pseudohypertrophic carriers by cloning and sequencing the deletion junctions, and explored the prospect of using deletion junctions in prenatal diagnosis of BMD.