Infantile intranuclear rod myopathy.

This report concerns three unrelated floppy infants, two girls and one boy, each biopsied at the age of 1 month. They were hypotonic since birth and required artificial ventilation. The two girls died at the ages of 4 and 3½ months, respectively, the boy is still alive at the age of 2 years, but requires assisted ventilation. Each of the three infants showed, by muscle biopsy, abundant intranuclear rods, the boy and one girl also had sarcoplasmic rods, which were not present in the other girl's muscle. Absence of sarcoplasmic rods, but the presence of intranuclear rods could also be documented in her autopsied muscle. Using an antibody against α-actinin, immunoelectron microscopy showed re…