X-linked myopathy with excessive autophagy: a clinicopathological study offive new families

In 1988, Kalimo et al. (Ann Neurol 23 (1988) 258)described a new type of X- linked myopathy in a Finnish family. The clinical course was characterized by slow progression of muscle weakness without loss of ambulation in childh ood and no evidence of cardiac, respiratory, or central nervous system invo lvement. Muscle fibers were not necrotic and showed excessive autophagic ac tivity and exocytosis of the phagocytosed material. These authors proposed the name X-linked myopathy with excessive autophagy. Subsequently, only one French family has been reported with similar clinical and histopathologica l data. We report here five new families with a total of eight affected boy s with the same clinical and histopathological features: as reported in the original families. Histopathological findings of an asymptomatic mother ar e also reported. Vacuolar changes in muscle fibers result both from invagin ations of the sarcolemma along with a variable component of basal lamina an d from an autophagic process. The complement C5b-9 membrane attack complex associated with MHC class 1 antigen and calcium deposits is involved in mus cle fiber damage. Among the X-linked myopathies. the identification of this new type is of great interest because of its favorable prognosis and uniqu e morphological findings. (C) 2001 Elsevier Science B.V. All rights reserve d.