Lactate dehydrogenase isoenzyme 5 in detecting carriers of duchenne muscular dystrophy

Thirty mothers of patients with Duchenne muscular dystrophy were studied with serum enzyme tests, including serum glutamic-oxaloacetic transaminase, creatine kinase, and lactate dehydrogenase isoenzymes. In addition, females from the mothers’ pedigrees were studied. Lactate dehydrogenase isoenzyme 5 determinations were as sensitive an indicator of carrier status as creatine kinase and also identified several mothers who had normal creatine kinase levels. The combination of creatine kinase and lactate dehydrogenase isoenzyme 5 determinations, as well as extensive pedigree testing, identified 28 of 30 mothers as probable heterozygotes. These data independently support the suggestion that cases of Duchenne muscular dystrophy as a result of spontaneous mutation are more uncommon than currently accepted.