[Evaluation of the activity of creatine phosphokinase for the detection of carriers of Duchenne-type muscular dystrophy in families in the city of Monterrey, Mexico].

The activity of serum creatine phosphokinase (CPK) was determined in 80 female members of 23 families with affected members of Duchenne type muscular dystrophy (DMD) and compared with the values of a control group of 100 unaffected women. The control group values exhibited a normal distribution of frequency with a mean of 21 U/L and standard deviation from the mean of 7.9 U/L. Sixty nine percent (11/16) of obligatory carriers showed CPK values higher than the mean of the control group plus two standard deviations of the mean. Thirty one percent (5/16) had false negative values. These percentages are similar to those reported in other studies. Elevated CPK activity was found in 45% (18/40) of type A possible carriers (relatives of obligatory carriers) and the group of possible carriers type B (mothers and relatives of isolated cases) 42% (10/24) exhibited high CPK values. Bayesian analysis was also used in all possible-carriers (A and B). We also report an estimation of the fertility of the DMD gene carriers and of their attitude towards family planning. It is concluded that the determination of serum CPK activity, despite its shortcomings, associated with Bayesian analysis when necessary, could be the method of choice for quick and inexpensive evaluation of the carrier status, mainly in families with members affected by DMD.