Fig. 2

Muscle biopsy from the deltoid muscle in case II:1 at age 24 years. A The majority of muscle fibers are larger than normal and many of them show internal nuclei. There are also scattered very small fibers (H&E). B The internal structure of the large fibers is slightly disturbed (NADH-TR). C Scattered regenerating fibers (arrow) (Immunostaining of embryonic MyHC). D-F Immunostaining of MyHC isoforms and perlecan; Slow/beta cardiac MyHC: blue, IIa MyHC: green, IIx MyHC: red and perlecan yellow, and for normal control, see Fig. 3F. D There is nearly type 1 fiber (blue) uniformity with a few scattered very small type 2A fibers (green, arrows). Some of these express also embryonic MyHC (asterisk in C and D). There are no type 2B fibers. E High magnification shows numerous extremely small type 2A fibers (arrows). F Some small fibers are hybrids, expressing both slow/beta cardiac MyHC and IIa MyHC (arrows)