Case of the month: germline mosaicism in carriers of Duchenne muscular dystrophy.

ABSTRACT

Carrier testing in a Duchenne muscular dystrophy (DMD) family resulted in the identification of a case of germline mosaicism. Using dystrophin cDNA probes, this phenomenon was ascertained by the demonstration of a deletion junction fragment present in the DNA of the affected patient and one sister but absent in the mother's DNA. As a result of this finding carrier risk estimations, based on restriction fragment length polymorphism (RFLP) studies, were significantly altered. The case demonstrates the importance of cDNA deletion carrier testing and the counseling implications of germline mosaicism.