Update on Congenital Myopathies in Adulthood

Abstract

Congenital myopathies (CMs) constitute a group of heterogenous rare inherited muscle diseases with different incidences. They are traditionally grouped based on characteristic histopathological findings revealed on muscle biopsy. In recent decades, the ever-increasing application of modern genetic technologies has not just improved our understanding of their pathophysiology, but also expanded their phenotypic spectrum and contributed to a more genetically based approach for their classification. Later onset forms of CMs are increasingly recognised. They are often considered milder with slower progression, variable clinical presentations and different modes of inheritance. We reviewed the key features and genetic basis of late onset CMs with a special emphasis on those forms that may first manifest in adulthood.

Keywords: adult onset congenital myopathies; inherited myopathies; late onset myopathies.

Figure 1

Muscle biopsies showing (a) prominent central nuclei (arrow) in a patient with centronuclear myopathy (H&E, ×20), (b) prominent central cores (arrow) in a patient with central core disease (NADH, ×20), (c) hypotrophy of type 1 muscle fibers (light) relative to type 2 (dark) in a patient with congenital muscle fiber disproportion (ATPase pH 9.4, ×20), (d) muscle fibers with nemaline rods (arrow) in a patient with nemaline myopathy (Gomori trichrome, ×40).