The present study included muscle biopsies from 12 infants (5 females and 7 males) with Werding-Hoffman's disease (WHO). The mean age of presentation was 11.8 months. Histo­ry of consanguinity was detected in 58.3%(7/12) of cases. The infants were presented with typical floppy baby pattern since birth or early in fi­rst few months of life. All had normal serum creatine phosphokinase level. The presence of large groups of atro­phied small fibres and large hypertro-phied muscle fibres is the classical microscopic picture. The histochemis-try showed that the atrophied and the hypertrophied muscle fibres are of type I and type II. The electron mi­croscopy showed disorganized Z bands in the atrophied muscle fibres.
the diagnosis of WHO needs correla­tion of the clinical picture, serum crea­tine phosphokinase, the elecromyo-graphy, the light microscopy, enzyme histochemistry and the electron mi­croscopy.