The use of serum creatine phosphokinase in genetic counseling for Duchenne muscular dystrophy: I. Analysis of results from 29 studies

Abstract

Several studies reported by various investigators using diverse methods of assay have been carried out to compare the serum creatine phosphokinase (CPK) activity in normal females and carriers of Duchenne muscular dystrophy (DMD), in an attempt to differentiate them biochemically. Results from different centers, even those using the same method of assay at the same temperature, are so divergent as to make simple pooling pointless, and collectively do not provide a satisfactory baseline for use by other clinics in genetic counseling. Examination of the method of moments estimates of the parameters suggests that the logarithm of the serum CPK activity in controls may be distributed normally and with stable variance. The degree of dispersion of CPK values, in controls, about the geometrical mean for each center has been estimated. The distribution in carriers is not so clear and no such maneuver seems appropriate.