Quantitative analysis of quadriceps muscle biopsy. Results in 7 definite and 45 possible carriers of Duchenne muscular dystrophy.

Quadriceps muscle biopsy was performed in 7 definite and 45 possible carriers of Duchenne muscular dystrophy. Unequivocal morphological changes were observed in 8 women; all but one of them were already detected as carriers by increased serum CK. Histometric analysis of muscle biopsy was performed on two fibre types (type 1 and type 2) in all 52 women; in 38 of them the two subgroups of type 2 fibres (type 2a and type 2b) were also quantified. Results of histometric analysis were matched with control values obtained from 30 healthy females in the same age as the carriers (20-50 yr). Histometric analysis on two fibre types detected a percentage of carriers (27%) much lower than that detected by serum CK determination (44%). The detection rate of combined serum CK determination and histometric analysis of muscle biopsy was: 100% in definite carriers, 65% in mothers possible carriers, 38% in sisters and 25% in the group of cousins and aunts. The histometric parameters most frequently altered were atrophy factor and variability coefficient of mean diameter. Histometric analysis carried out on three fibre types in 38 women detected 2 more carriers showing atrophy of type 2b fibres. The results indicate that quantitative analysis of muscle biopsy may be used to detect some possible carriers with normal serum CK. However, an adequate number of controls is mandatory; in fact the detection rate of histometric analysis of muscle biopsy decreased by increasing the number of controls, resulting much lower than previously reported.