[Identifying deletions in the dystrophin gene and detecting carriers in families with Duchenne's/Becker's muscular dystrophy].

INTRODUCTION: Between 60 and 65% of the mutations that cause Duchenne's/Becker's muscular dystrophy (DMD/BMD) are deletions in the dystrophin gene. Identifying deletions confirms the diagnosis and allows carriers to be detected with precision, which is the main preventive resource. The frequency and distribution of deletions in the DMD gene is unknown in south-east Mexico.

AIMS: To identify deletions in the DMD gene and to detect carriers in families with DMD/BMD in south-east Mexico.

PATIENTS AND METHODS: The study involved 26 families that showed clinical signs of DMD/BMD: Deletions were determined in the DNA of 40 males by means of the multiple polymerase chain reaction (PCR) in 22 segments of the gene. Detection of carriers was applied to 33 female relatives using PCR-restriction fragment length polymorphism of the polymorphic markers Pert 87.8/Taq 1, pERT 87.15/Bam H1, and single PCR for VNTR MP1P by linkage analysis.

RESULTS: Deletions were identified in 67.5% of patients with DMD and they were located in the 5' end and in the central region, exons 44 to 52, of the gene. In the detection of carriers, 73.33% of the families were informative. The markers 87.8/Taq 1 and MPIP yielded the greatest information power, with 26.67 and 33.33%, respectively. Of a total of 33 females, 21 (63.64%) were carriers, one (3.03%) was a non-carrier and 11 (33.33%) were not informative.

CONCLUSIONS: The frequency of deletions was 67.5%. Carrier status was determined in 66.67% of the females who were analysed. The markers pERT 87.8/Taq 1 and MP1P yielded the greatest information power.