A new distal myopathy with mutation in anoctamin 5.

We have been following clinically and with muscle MRI for the past 3-decades a Finnish family with two patients with distal muscular dystrophy. Previously we demonstrated the cellular defect in these patients to be defective membrane repair and more recently have identified the causative gene to be anoctamin 5 (ANO5). The disorder seen in these patients is characterized by onset in the third decade. First symptoms were burning sensation on the calves and later on calf tightness during running. Muscle weakness and wasting were asymmetric and early involving the calf muscles, later spread to the thigh muscles. Biceps brachi was later manifestation. Clinical course was slow. CK levels were high. Muscle biopsy showed dystrophic pattern and multifocal disruption of the sarcolemmal membrane but no subsarcolemmal vesicle accumulation nor active inflammation. We conclude that the disease seen in our cases is a new separate clinical, genetic and histopathologic entity to include within the classification of autosomal recessive distal muscular dystrophies.