In a family with spinal muscular atrophy, the distinctive clinical features were (1) juvenile onset; (2) scapulohumero-peroneal muscular atrophy and weakness; (3) cardiopathy with conduction defect; and (4) probable X-linked recessive inheritance. Marked limitation of the neck flexion due to shortness (or atrophy) of posterior nuchal muscles and shortness of the Achilles tendons were early manifestations. A similar but milder electrocardiographic abnormality was found in the mothers of the patients; female carriers may have a latent cardiopathy. The ECG abnormalities suggest a selective disorder of the conduction system. This seems to be a new clinical entity.
Mawatari S, Katayama K. Scapuloperoneal Muscular Atrophy With Cardiopathy: An X-Linked Recessive Trait. Arch Neurol. 1973;28(1):55–59. doi:10.1001/archneur.1973.00490190073010
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