Patient 1 was a 30-yr-old woman complaining of progressive limb muscle weakness. She was in good health until age 12 yr, at which time she began to have a difficulty in raising her right arm above her head. Later, she developed increasing difficulties climbing stairs. By report, her mother had similar symptoms from the age of 40. His 35-yr-old brother was not affected clinically (). The neurological examination was remarkable for moderate facial weakness; moderate (Medical Research Council [MRC] grade 3) and mild (MRC grade 4) weakness of proximal upper and lower limb muscles, respectively; humeral atrophy; anterior axillary folds; winged scapulae; waddling gait; and hypoactive deep tendon reflexes. The serum creatine kinase (CK) was 233 IU/L (normal, <270 IU/L). Other routine laboratory tests including thyroid and parathyroid function were normal. Audiogram, electrocardiogram, echocardiogram, nerve conduction studies were unremarkable. Needle electromyography showed chronic myopathic changes in the left deltoid, biceps brachii, and vastus lateralis muscles. A muscle biopsy from the right vastus lateralis revealed marked fiber size variations, increased internalized nuclei, endomyseal fibrosis and fat ingrowth, and frequent lobulated myofibers.
Patient 4 was a 46-yr-old man presenting with progressive limb muscle weakness developed in his early twenties. He first noticed a difficulty in raising his arm above his head. There was no known family history of neuromuscular disease in his parents, five sibs, and two daughters (). The neurological examination was remarkable for mild (MRC grade 4) weakness of proximal upper limb muscles and humeral atrophy. Other remarkable findings included anterior axillary folds, asymmetric winged scapulae, trapezius hump sign, Beever's sign, and hypoactive deep tendon reflexes. There was no facial weakness. The serum CK was 170 IU/L. The FVC was 4.19 L (87% of predicted). Electrocardiogram, echocardiogram, and nerve conduction studies were normal. Needle electromyography showed chronic myopathic changes.