POMT1/2 enzymatic activity can be measured in both fibroblasts and lymphocytes, and this has been exploited as a diagnostic test in patients with mutations in these 2 genes. It has also been proposed that the finding of reduced POMT enzymatic activity could be used as a more rapid form of PI3K Inhibitor Library patient screening (53). Targeted inactivation of Pomt1 has been achieved in mice but is embryonic lethal in the homozygous

mice due to defects in the formation of Reichert’s membrane, the Inhibitors,research,lifescience,medical first basement membrane to form in the mouse embryo which requires normally glycosylated dystroglycan (54). The POMGnT1 gene The POMGnT1 gene encodes protein O-linked mannose β1,2-N-acetylglucosaminyltransferase 1, an enzyme involved in the transfer of an N-acetylglucosamine residue to an O-linked mannose (25). Mutations in POMGnT1 were originally identified in patients affected by typical MEB, Inhibitors,research,lifescience,medical a condition characterized by CMD together with cortical dysplasia and ocular

involvement (20). Following the original demonstration of POMGnT1 mutations in the Finnish and Turkish MEB patient population, collaborative papers highlighted the spectrum of phenotypes in a world wide study, which ranged from typical MEB to more severe patients with structural brain involvement overlapping WWS. Mutations located at the 5’ end of the gene were on the whole associated Inhibitors,research,lifescience,medical with a more severe phenotype than those located at the 3’ end of the gene (55). POMGnT1 enzymatic activity can also be measured Inhibitors,research,lifescience,medical from frozen muscle, lymphocytes and fibroblasts (56). Regarding the spectrum of clinical severity in patients with POMGnT1 mutations, our group very recently identified Inhibitors,research,lifescience,medical a patient with a form of LGMD with onset in the second decade of life, with entirely normal intelligence, who followed a relatively rapid progression of muscle weakness, becoming wheelchair dependent aged 19 following a fracture. Enzymatic studies on the patient’s fibroblasts showed an altered kinetic profile, however this

was less marked than in patients with MEB, and in keeping with the patient’s relatively Thymidine kinase mild phenotype. This patient therefore is the mildest patient with POMGnT1 mutations reported so far and her phenotype is that of a LGMD with proximal muscle weakness and markedly elevated serum CK (Clement et al., manuscript in press). An animal model of MEB due to mutations in POMGnT1 exists, following the introduction of null alleles in this gene. These mutant mice were viable with multiple developmental defects in muscle, eye, and brain, similar to the phenotypes observed in human MEB disease (57, 58). The Fukutin gene Fukuyama-type congenital muscular dystrophy (FCMD) is a condition confined to Japan. Similar to MEB and WWS, it is characterized by the combination of CMD and central nervous system involvement.