Prenatal diagnosis of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is one of the most common X-linked genetic disorders seen in children. Mutations in the DMD gene coding for the protein dystrophin causes the severe muscle-wasting disorder leading to death in the second decade of life. In the absence of a cure, prenatal diagnosis (PND) appears to be the best approach to reduce the burden of this disease on the individual family and ultimately on society. There are few published reports worldwide on PND and very few from the developing countries. We report our experience with PND for families with DMD using multiplex polymerase chain reaction (PCR) and microsatellite polymorphic marker analysis.

From August 1997 to October 1999, PND was offered on request to 23 families with one or two boys affected with DMD. A total of 26 foetuses were screened for DMD. Initially the deletions in the DMD gene in the affected child were identified by multiplex PCR screening for 23 exons in 6 sets. In patients where deletions were not identified, microsatellite repeat analysis was carried out to follow the inheritance of the mutant allele. DNA was extracted from chorionic villus samples obtained by chorionic villus biopsy performed at 10-15 weeks of gestation in 17 families, and at 16-20 weeks in 6 families.

Deletions were identified in 20 affected boys. In 2 families, microsatellite repeat analysis was done to identify the mutant allele. Of the 26 foetuses, 5 were found to be affected with DMD and the parents opted for termination of pregnancies.

Multiplex PCR technology and microsatellite repeat analysis can be used effectively for PND of DMD.