Vici syndrome is a rare, genetically unresolved congenital multi-system disorder comprising agenesis of the corpus callosum, cataracts, immunodeficiency, cardiomyopathy, and hypopigmentation. An associated neuromuscular phenotype has not previously been described in detail. We report on an infant with clinical features suggestive of Vici syndrome and additional sensorineural hearing loss. Muscle biopsy revealed several changes including markedly increased variability in fiber size, increased internal nuclei, and abnormalities on Gomori trichrome and oxidative stains, raising a wide differential diagnosis including neurogenic atrophy, centronuclear myopathy (CNM) or a metabolic (mitochondrial) cytopathy. Respiratory chain enzyme studies, however, were normal and sequencing of common CNM-associated genes did not reveal any mutations. This case expands the clinical spectrum of Vici syndrome and indicates that muscle biopsy ought to be considered in infants presenting with suggestive clinical features. In addition, we suggest that Vici syndrome is considered in the differential diagnosis of infants presenting with congenital callosal agenesis and that additional investigation has to address the possibility of associated ocular, auditory, cardiac, and immunologic involvement when this radiologic finding is present. (C) 2010 Wiley-Liss, Inc.