An assessment of the creatine kinase test in the detection of carriers of Duchenne muscular dystrophy

Abstract

Serum creatine kinase activity has been utilized to evaluate the probability that female relatives of a patient with Duchenne muscular dystrophy are heterozygous. Each possible carrier was classified genetically on the basis of whether the risk that she is heterozygous is known or unknown. Although only 65 per cent of definite carriers could be identified by elevated creatine kinase activity, there was close agreement between the number of possible carriers with elevated creatine kinase and the number expected to be heterozygous. These observations could be explained on the basis of age differences in creatine kinase activity in heterozygotes, and suggest that carrier detection studies should be performed at an early age. Comparison of creatine kinase activity in mothers who are definite carriers and mothers of isolated cases shows that approximately fifty per cent of mothers of isolated cases are heterozygous.