Successful carnitine treatment in two siblings having lipid storage myopathy with hypertrophic cardiomyopathy.

Two Japanese siblings had lipid storage myopathy with hypertrophic cardiomyopathy (HCM). They had slowly progressive muscle weakness and ventricular hypertrophy of the heart evidenced by electrocardiography and echocardiography. Their developmental milestones were normal until three years of age when mild weakness in the lower limbs became evident. Laboratory examination showed transient high creatine kinase levels (CK) and hyperammonemia. Histochemical investigation on the muscles revealed abnormal accumulation of sudanophilic lipid droplets predominantly in type 1 fibers, type 2 A fiber atrophy and type 2 B fiber deficiency. In case 1, excessive lipid droplets were also observed in the biopsied cardiac muscle. Carnitine was decreased in the skeletal muscles and the serum. Treatment with DL-carnitine to both cases resulted in marked clinical improvement and decreased lipid droplets in the muscles.