Familial neuromuscular disease with “myotubes“

Van Wijngaarden et al. (1969) described a “myotubular myopathy” in a Dutch family, of which six male members were affected, indicating a recessive X‐linked mode of transmission. They also thought that the morphology of a case reported by Engel et al. (1968) resembled that seen in their family. The present case is a male sib of the patient reported by Engel and colleagues, who has similar clinical and morphologic features to his brother, and who died at 7 months of age. Muscle enzyme histochemistry of a quadriceps biopsy revealed that most type I fibers were small and had central pale areas or plump nuclei. A smaller percentage of type II fibers also showed the same features. Biopsies of muscle from the mother and father were histologically normal including fiber type composition. Karyotypic analyses, not reported in earlier cases, were performed on the family and showed no abnormalities in modal number or of individual chromosome structure. Pedigree analysis suggests an X‐linked recessive inheritance pattern in this family.