Muscle-eye-brain disease is a congenital muscular dystrophy characterized by structural brain and eye defects. Here, we describe a 12-year-old boy with partial agenesis of corpus callosum, ventriculomegaly, flattened brain stem, diffuse pachygyria, blindness, profound cognitive deficiencies, and generalized muscle weakness, yet without a clear dystrophic pattern on muscle biopsy. There was no glycosylation of α-dystroglycan and the genetic screening revealed a novel truncating mutation, c.1545delC (p.Tyr516Thrfs*21), and a previously identified missense mutation, c.1469G>A (p.Cys490Tyr), in the protein O-mannose beta-1,2-N-acetylglucosaminyltransferase 1 (POMGNT1) gene. These findings broaden the clinical spectrum of muscle-eye-brain disease to include pronounced hypotonia with severe brain and eye malformations, yet with mild histopathologic changes in the muscle specimen, despite the absence of glycosylated α-dystroglycan.
Keywords: POMGNT1; dystroglycan; dystroglycanopathy; glycosylation; muscle-eye-brain disease.