Qualitative or quantitative defects of protein O-mannosyltransferase 1

Qualitative or quantitative defects of protein O-mannosyltransferase 1 (POMT1) refer to genetic abnormalities affecting the POMT1 gene, which encodes an enzyme critical for the O-mannosylation of alpha-dystroglycan. Alpha-dystroglycan is a key component of the dystrophin-glycoprotein complex, which links the intracellular cytoskeleton to the extracellular matrix in skeletal muscle, brain, and eye tissues. Defective O-mannosylation of alpha-dystroglycan leads to a group of conditions collectively known as dystroglycanopathies. POMT1 mutations can cause a spectrum of disease severity, ranging from the most severe form, Walker-Warburg syndrome (WWS), to milder limb-girdle muscular dystrophy type 2K (LGMD2K, now classified as LGMDR11). Walker-Warburg syndrome, the most severe phenotype associated with POMT1 deficiency, presents at birth with severe congenital muscular dystrophy, profound structural brain abnormalities (including cobblestone lissencephaly, hydrocephalus, and cerebellar malformations), and eye anomalies (such as microphthalmia, retinal detachment, and cataracts). Affected infants typically have severe intellectual disability and markedly reduced life expectancy, often surviving less than three years. Milder POMT1-related phenotypes, such as LGMD2K, present later in childhood with progressive proximal muscle weakness, elevated serum creatine kinase levels, and variable degrees of intellectual disability, but without the severe brain and eye malformations seen in WWS. There is currently no cure for POMT1-related dystroglycanopathies. Treatment is supportive and multidisciplinary, involving neurological, orthopedic, ophthalmological, and rehabilitative care. Physical therapy, respiratory support, seizure management, and nutritional support are important components of care. Genetic counseling is recommended for affected families. Research into gene therapy and other molecular approaches is ongoing but remains in early stages.

Common questions about Qualitative or quantitative defects of protein O-mannosyltransferase 1