Intragenic deletion in the LARGE gene causes Walker-Warburg syndrome

Intragenic homozygous deletions in the Large gene are associated with a severe neuromuscular phenotype in the myodystrophy (myd) mouse. These mutations result in a virtual lack of glycosylation of alpha-dystroglycan. Compound heterozygous LARGE mutations have been reported in a single human patient, manifesting with mild congenital Muscular Dystrophy (CMD) and severe mental retardation. These mutations are likely to retain some residual LARGE Glycosyltransferase activity as indicated by residual alpha-dystroglycan glycosylation in patient cells. We hypothesized that more severe LARGE mutations are associated with a more severe CMD phenotype in humans. Here we report a 63-kb intragenic LARGE deletion in a family with Walker-Warburg syndrome (WWS), which is characterized by CMD, and severe structural brain and eye malformations. This finding demonstrates that LARGE gene mutations can give rise to a wide clinical spectrum, similar as for other genes that have a role in the post-translational modification of the alpha-dystroglycan protein.