Diphenoloxidases in various forms of myopathy which are transmitted by different genetic mechanisms.

In a previous article (Demos et al. 1981), we reported a significant and specific reduction of the activity index (AI) of the diphenoloxidases (DPox) in patients and heterozygotes with progressive Duchenne muscular dystrophy (DMD), which is transmitted genetically by female subjects by a sex-linked recessive mechanism (SLR). This same anomaly was detected in patients suffering from other types of dystrophy: Becker, limbgirdle, fascio-scapulo-humeral, and in heterozygotes of either sex in diseases transmitted by an obviously recessive autosomic mechanism. These anomalies were detected using blood spots collected on absorbent paper and stored at 4 degrees C for different periods. They were of the same type as had previously been detected using blood platelets (Demos 1973).

Diphenoloxidases in X-linked recessive (Duchenne) muscular dystrophy.

In extracts derived from whole blood, a high molecular weight fraction of the diphenoloxidase enzymes has a significantly diminished specific activity in patients and definite carriers (heterozygotes) of the X-linked, recessive (Duchenne) form of muscular dystrophy. This anomaly was studied using spots of blood which had been collected on absorbent paper and stored at 4 degrees C for variable periods of time. Fractions enriched in the enzymes were obtained by subjecting aqueous extracts of the spots to treatment with an anion exchange resin (DEAE Sephadex A 50) followed by gel filtration on Sephadex G-25. It is of interest that this anomaly was observed in some definite carriers of the mutant gene who had on several occasions a serum creatine kinase level in the normal range. The significance of these observations is discussed.