Abstract: Objective To investigate the value of the junction fragments between the breakpoints of introns in identifying
deletional Duchenne muscular dystrophy (DMD) carriers. Methods A 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. Results PCR 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. Conclusion Routine PCR technique for detecting the junction fragments allows
identification of carriers among female relatives of patients with deletional DMD.