DMD/BMD – OUTCOME MEASURES: EP.132 Double the trouble: familial hyperlipidemia and Becker muscular dystrophy with a hemizygous nonsense mutation in the dystrophin (DMD) gene

Abstract

Becker muscular dystrophy (BMD) is an X-linked recessive disorder caused by the absence of dystrophin. It is characterized by progressive skeletal and cardiac muscle weakness that usually becomes apparent between the ages of 5 and 15. Familial hypercholesterolemia (FH) is an autosomal dominant disorder of lipid metabolism present from birth. It is characterized by remarkably high low-density lipoprotein cholesterol (LDL-C) levels causing premature coronary heart disease. We report a 9-year-old boy with familial hyperlipidemia who presented with creatinine kinase elevation. He was born after uneventful pregnancy and delivery with consanguineous marriage of his parents. The motor developmental milestones were normal. On physical and neurological examination at the age of 9, he had only mild pseudohypertrophy in the gastrocnemius muscles. Gowers’ sign was negative. He had no myotonia or muscle weakness. The cardiological evaluation was unremarkable. Serum creatine kinase (CK) level was elevated (2889 UI/L). Moreover, serum triglyceride (183 mg/dl), VLDL cholesterol (37 mg/dl), LDL cholesterol (212 mg/dl), and total cholesterol (289 mg/dl) were elevated. We identified a heterozygous mutation of c.1246 C>T (p.R416W) (paternal) in the LDLR gene and a hemizygous nonsense mutation of c.71G>A (p.W24) in the DMD gene. Based on the clinical manifestations, examination, and laboratory findings, we diagnosed BMD and familial hyperlipidemia. We described a case with familial hyperlipidemia presented with serum creatinine kinase (CK) elevation and identified hemizygous nonsense mutation of c.71G>A p.W24 in the dystrophin gene.