Identification of Duchenne and Becker MuscularDystrophy Carriers by Fluorescence In SituHybridization

Overview

Duchenne and Becker muscular dystrophies (DMD/BMD) are X-linked recessive disorders causedby mutations in the dystrophin gene. A large intragenic deletion has been described in about 65%of DMD/BMD patients. Mothers of affected males are DMD/BMD carriers in two thirds of thecases. Routine deletions detection in DMD/BMD males is performed using multiplex polymerasechain reaction (mPCR), RT-PCR with a protein truncation test (PTT) or using Southern blotting.In females the deletions detection is complicated by the presence of a normal gene copy on thesecond X-chromosome. We are presenting the diagnostic strategy using FISH for the deletionsdetection in the dystrophin gene of female DMD/BMD carriers. We have used a set of six cosmidprobes for the detection of the most frequently deleted areas of the dystrophin gene from theDepartment of Human Genetics, Leiden University Medical Center. We have examined 14 mothersof DMD/BMD males with a deletion in the dystrophin gene identified using mPCR. Four mothersof affected males have been diagnosed as carriers of a deletion in the dystrophin gene. We haverevealed no deletion mutations in the exons examined in a control group of four healthy females.No discrepancy has been found between the FISH analysis results and the results of mPCR.Our results indicate that FISH is an effective and direct method for the identification ofDMD/BMD carriers and we suggest this method as a method of a first choice in the identificationof DMD/BMD carriers.

Key words:
Duchenne muscular dystrophy (DMD) - deletions - FISH