[The first Japanese case of autosomal dominant Emery-Dreifuss muscular dystrophy with a novel mutation in the lamin A/C gene]

Abstract

Emery-Dreifuss muscular dystrophy (EDMD) is a muscular disorder characterized by 1) early contracture of the elbows. Achilles tendons and post-cervical muscles, 2) slowly progressive muscle wasting and weakness with a humeroperoneal distribution, and 3) life-threatening cardiomyopathy with conduction block. Most of families with EDMD show X-linked recessive inheritance with mutations in the STA gene on chromosome Xq28, which encodes a protein named emerin. A rare autosomal dominant form of EDMD (AD-EDMD) is caused by mutations in lamin A/C gene (LMNA) on chromosome 1q21. Both emerin and lamin A/C are located in the inner surface membrane of the nucleus. A 49-year-old woman was skinny and slow runner from childhood and suspected as having a certain muscular disorder. At 35 years, she was found to have the second degree atrioventricular block. At 45 years, she was admitted to a hospital for right-side hemiplegia after cerebral infarction. Cardiac involvement was also observed including high degree atrioventricular block with chronic atrial fibrillation and frequent paroxysmal ventricular contraction on the electrocardiogram. At 49 years, she was referred to our hospital for further evaluation. She had possible dilated cardiomyopathy with conduction block. She also had muscular atrophy and weakness in all extremities, predominantly in the right-side, and contracture of bilateral Achilles tendon, knee and elbow joints, and postcervical muscles. Biopsied skeletal muscle and electromyogram showed myopathic changes. Since a novel point mutation of Ser303Pro was found in exon 5 of LMNA gene, she was diagnosed as having AD-EDMD and had a permanent pacemaker implantation. Her daughter also had some abnormalities on electrocardiogram. This is the first Japanese case of AD-EDMD. Amiodaron was effective for non-sustained ventricular tachycardia. Early diagnosis and following cardiological examinations and treatments are important and necessary to improve the prognosis of the patients with EDMD.