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.
Patient 3 was an 18-yr-old man complaining of progressive right upper limb weakness over the prior 3 yr. The initial diagnosis was idiopathic right brachial plexopathy. He was a tennis player in his early teens. There was no family history of neuromuscular disease (). Clinical examination of his parents was normal. Remarkable neurological findings included mild bifacial weakness; mild (MRC grade 4) and minimal weakness of the right and left proximal upper limb muscles, respectively; winged scapulae in the right side; and hypoactive deep tendon reflexes. The serum CK was 750 IU/L. Other routine laboratory tests including thyroid function were normal. Audiogram, electrocardiogram, echocardiogram, and nerve conduction studies were unremarkable. The FVC was 4.2 L (98% of predicted). Needle electromyography revealed chronic myopathic changes.