Immunostaining of biopsied skeletal muscle of 4 Duchenne (DMD), 12 Bec
ker muscular dystrophy (BMD) and 3 DMD carriers' was performed using m
onoclonal antibodies against dystrophin and utrophin. In DMD, dystroph
in-negative staining was observed except for revertant fibers which sh
owed different stain patterns for each antibody. In 7 BMDs, there was
faint/patchy stain in cases of deletion between exons 45-52, while in
one case there was deletion between exons 12-17 and no stain was noted
relevant to the deletion site. Moreover, in 2 cases of undetectable d
eletion, antibodies which recognize a terminal portion of the C-termin
al domain revealed the absent stain. In DMD, the utrophin-positive fib
ers corresponded to dystrophin-negative fibers. In BMD, this relations
hip did not necessarily occur in each fiber. In DMD carriers, a cluste
r of dystrophin-negative fibers which was positive for utrophin were p
rominent. In dystrophinopathy, the immunostaining of dystrophin and ut
rophin is useful, in combination with dystrophin gene analysis to make
a definite diagnosis.