[Prenatal molecular diagnosis of a DMD carrier female fetus by chorionic villus sampling and linkage analysis]

Abstract

Background: Duchenne muscular dystrophy (DMD) is the most frequent inherited and lethal neuromuscular disorder in humans. Molecular prenatal diagnosis of DMD through amniocentesis is a real preventive reproductive option in our country, although experience with chorionic villus sampling is still limited (CVS).

Objective: Perform the first prenatal diagnosis in an obligate DMD carrier woman in Mexico by CVS.

Material and method: CVS was performed in an obligate DMD carrier woman in which no partial intragenic deletions were present but a haplotype at-risk was identified. Cytogenetic analysis with GTG banding was performed and genomic DNA extraction from CVS sample was done without culture. Fetal gender assignment was achieved by ultrasonography at 12 weeks of gestation and confirmed by PCR amplification of two Y chromosome-linked loci (SRY and DYS389I/II). Identification of the DMD haplotype at-risk in the fetus was done through analysis of the intragenic markers pERT87.8/TaqI and pERT87.15/Xmnl.

Results: Absence of PCR products corresponding to Y chromosome-linked loci in DNA CVS sample was compatible with a female fetus; it was confirmed later by cytogenetic study and prenatal ultrasound follow-up. Linkage analysis reveals that the female fetus inherited the DMD haplotype at-risk. We did not identify any maternal DNA contamination in CVS molecular analysis and these results were postnatally confirmed in DNA obtained from buccal cells.

Conclusion: Molecular prenatal diagnosis through chorionic villus sampling could be an early reproductive prevention strategy applicable to Duchenne/Becker muscular dystrophy carrier women in our country.