Hereditary lactate dehydrogenase M-subunit deficiency: lactate dehydrogenase activity in skin lesions and in hair follicles.

A 16-year-old Japanese girl had desquamating erythematosquamous lesions mostly on the extensor surface of the extremities. The lesions were worse in summer. The patient also had a mild muscle pain after strenuous exercise. Her paternal and maternal grandfathers are cousins. An analysis of lactic acid dehydrogenase (LDH) isozymes in her serum revealed a single peak of LDH1. Analysis of LDH isozymes of erythrocytes demonstrated a complete lack of LDH M-subunit in the patient and a substantial lack in the parents. The epidermis of the diseased skin and scalp hair follicles of the patient were virtually devoid of LDH activity.