A mild juvenile variant of type IV glycogenosis.

The mild juvenile form of type IV glycogenosis, confirmed by a profound deficiency of the brancher enzyme in tissue specimens is reported from three Turkish male siblings who, foremost, suffered from chronic progressive myopathy. Muscle fibers contained polyglucosan inclusions of typical fine structure i.e. a mixture of granular and filamentous glycogen. They reacted strongly for myophosphorylase, but were resistant to diastase. These inclusions were ubiquitinated and reacted with antibody KM-279 which previously has been shown to bind to Lafora bodies, corpora amylacea and polyglucosan material in hepatic and cardiac cells of type IV glycogenosis as well as polyglucosan body myopathy without brancher enzyme deficiency. Our findings confirm that although rate, a mild form of type IV glycogenosis is marked by polyglucosan inclusion not only in myofibers, but also in smooth muscle and sweat gland epithelial cells. This further implies that when polyglucosan inclusions are observed within myofibers it is mandatory to examine the muscle tissue for brancher enzyme activity since the brancher enzyme activities in circulating erythrocytes and leucocytes were normal in all three affected siblings and their parents. Therefore, it can be concluded that the patients reported on here represent a variant form of type IV glycogenosis, in which the defect is limited to muscle tissue. This further indicates that there are several different types of type IV glycogenosis with variable clinical manifestations.