Intramuscular interstitial amyloid deposition does not impact anoctaminopathy-5 phenotype.

Abstract

Recessive mutations in the anoctamin-5-encoding gene (ANO5) cause muscular dystrophy of various phenotypes. Intramuscular interstitial amyloid deposits were detected in a few patients with anoctaminopathy-5, some with cardiac involvement. The frequency of amyloid deposition in anoctaminopathy-5 and its impact on phenotype are unknown. We retrospectively identified patients with genetically proven anoctaminopathy-5 who had undergone muscle biopsy and reviewed their clinical and laboratory data. Eight of 15 patients with anoctaminopathy-5 had intramuscular interstitial amyloid deposits. The median age at onset of weakness was 40 and 45 years in the amyloidosis and nonamyloidosis groups, respectively. Mutations occurred throughout the entire gene in the amyloidosis group. Atrial arrhythmia was noted in 4 patients with amyloidosis and in 4 patients without amyloidosis. The latter group also had premature ventricular contractions. One nonamyloidosis patient had septal hypokinesia. Intramuscular amyloidosis occurred in 53% of patients with anoctaminopathy-5 who underwent muscle biopsy and had no impact on the phenotype. Muscle Nerve 59:133-137, 2019.