Facioscapulohumeral dystrophy presenting as infantile facial diplegia and late-onset limb-girdle myopathy in members of the same family.

We report a family with markedly variable myopathic weakness due to facioscapulohumeral muscular dystrophy (FSHD). The proband developed mild late-onset proximal limb weakness. Her two daughters had severe infantile facial diplegia, initially diagnosed as Möbius syndrome, and mild childhood-onset limb weakness and scapular winging. Results of facial muscle electromyography and muscle histopathology supported a myopathic disorder. This case study further highlights the broad clinical spectrum and intrafamily variability in FSHD, and the occasional absence of a positive correlation between fragment size and disease onset. Moreover, this study underscores the importance of considering FSHD in cases of infantile facial diplegia, especially in patients not demonstrating the full clinical features of Möbius syndrome. In difficult cases, facial muscle electromyography may help to differentiate myopathic from neuropathic weakness, and help guide further diagnostic studies.