A Novel Mutation of the GNE Gene in Distal Myopathy with Rimmed Vacuoles: A Case with Inflammation
A 40-year-old Thai man had developed gradual but progressive left leg and left arm weakness over 7 years. He could not flex his left foot upward and had difficulty using the left hand. He also noticed weakness on his right leg and right hand for the last 4 years. Physical examination revealed muscle atrophy in both arms and legs. The muscle volume and strength of distal muscles on both sides of the extremities were markedly decreased, especially in the forearms, hands, and feet. Motor power of both sides of the body rated by the Medical Research Council Scale was as follows: tibialis anterior 2/5, quadriceps 4/5, gastrocnemius and soleus 5/5, forearm flexors and intrinsic hand muscles 3/5, and triceps and biceps 5/5. The muscle strength of deltoid and supraspinatus on the left side was 4/5 but 5/5 on the right side. The deep tendon reflexes at the ankle were diminished. There was no other neurologic abnormality. There was no clinical or laboratory evidence of systemic or connective tissue diseases. Serum creatine kinase (CK) was mildly increased to 293 IU/l. He was initially treated with corticosteroids but there was no significant clinical improvement. A nerve conduction study and electromyogram were consistent with chronic myopathy predominantly involving the intrinsic hand muscles and tibialis anterior muscles. Whole-spine magnetic resonance imaging was within normal limits. Magnetic resonance imaging of the muscles was not performed. There was no history of muscle disease or consanguineous marriage in his family. The patient was partially wheelchair-bound but could walk with assistance.