Novel ANO5 homozygous microdeletion causing myalgia and unprovoked rhabdomyolysis in an Arabic man

Abstract

Introduction: Recessive mutations in the anoctamin-5 gene (ANO5) cause a spectrum of clinical phenotypes, including limb-girdle muscular dystrophy (LGMD 2L), distal myopathy, and asymptomatic hyperCKemia.

Methods: In this report we describe our clinical, electrophysiological, pathological, and molecular findings in a subject with anoctaminopathy-5.

Results: A 49-year-old Arabic man from a consanguineous family presented with a 5-year history of myalgias, hyperCKemia and an episode of unprovoked rhabdomyolysis. Muscle biopsy showed mild myopathic changes and interstitial amyloid deposition. ANO5 analysis detected a novel homozygous deletion of approximately 11.9 kb encompassing exons 13-17, predicted to be pathogenic.

Conclusions: Anoctaminopathy-5 can manifest with a phenotype reminiscent of metabolic myopathy and should be considered as a potential cause of myalgia and myoglobinuria. Amyloid deposition in the muscle biopsy is helpful for the diagnosis. A novel homozygous ANO5 deletion was identified, suggesting that screening for common mutations may have low yield in non-European subjects.

Keywords: ANO5; ANO5 deletion; amyloidosis; anoctaminopathy; hyper-CK-emia; muscular dystrophy; pseudometabolic myopathy; rhabdomyolysis.