A new method for the analysis of age trends in CPK levels with application to Duchenne muscular dystrophy.

Measurement of serum creatine phosphokinase (CPK) is the most commonly applied test for carrier detection in Duchenne muscular dystrophy. About two thirds of all carriers have markedly elevated CPK levels. Age correction of CPK measurements would be straightforward if carriers of all ages could be unambiguously identified. Since such identification is impossible, we elaborate an indirect statistical method which is based on Haldane's theory of the balance between selection and mutation for X-linked lethals. We also apply this method to a large body of data gathered on female relatives of Duchenne muscular dystrophy patients and on controls. The results are compared with earlier partial findings.