Limb-Girdle Muscular Dystrophy Type 2K

Abstract

LGMD2K is caused by mutations in the POMT1 gene, encoding for O-mannosyl-transferase-1 protein (Table 16.1), and results from defective glycosylation of alpha-dystroglycan. This disorder represents the mildest end of the phenotypic spectrum of muscular dystrophies collectively known as dystroglycanopathies. The phenotype is characterized by weakness apparent after walking is achieved; mental retardation and mild brain anomalies are variable. The most severe end of the phenotypic spectrum of dystroglycanopathies is represented by congenital muscular dystrophy with brain and eye anomalies, previously designated Walker-Warburg syndrome (WWS) or muscle-eye-brain disease (MEB), and the intermediate range of the spectrum is represented by congenital muscular dystrophy-dystroglycanopathy with or without mental retardation.