OBJECTIVETo investigate the value of the junction fragments between the breakpoints of introns in identifying deletional Duchenne muscular dystrophy (DMD) carriers.

METHODSA DMD family (including the index patient III2 and the suspected carrier II3) and a sporadic DMD case (including the patient II1 and his mother I2) were studied. The patient III2 of the DMD family was identified as having exons 31-43 deletion of the DMD gene, and the sporadic patient II1 had exons 45-54 deletion. A PCR-based genome-walking method was used to locate the breakpoints in the corresponding introns. The junction fragments of the patients and their female relatives waiting for a diagnosis were amplified by PCR with primers adjacent to the deletion junctions.

RESULTSPCR amplification yielded identical positive results for the female suspected carrier II3 of and the index patient of the DMD family, and the former was thus diagnosed as a carrier of DMD. PCR amplification of the sporadic patient's mother I2 showed a negative result, but the patient II1 had a positive result, so that the patient's mother was excluded as being a carrier of DMD.

CONCLUSIONRoutine PCR technique for detecting the junction fragments allows identification of carriers among female relatives of patients with deletional DMD.