Muscle-Eye-Brain Disease and Other POMGNT1-Related Congenital Muscular Dystrophy-Dystroglycanopathies (POMGNT1)
POMGNT1-related congenital muscular dystrophy-dystroglycanopathies are a group of autosomal recessive neuromuscular diseases caused by pathogenic variants in the gene POMGNT1. While they are found in individuals of different ethnicities, they are more prevalent in individuals of Finnish descent due to the presence of a founder mutation. The POMGNT1-related congenital muscular dystrophy-dystroglycanopathies vary in severity. Type A3 (also known as muscle-eye-brain disease), which is both the most common and the most severe, has an onset at birth or sometimes in the prenatal period. It is characterized by severe brain malformations and intellectual disability, seizures, vision problems, and hypotonia. Death usually occurs in the first year of life. Type B3 is characterized by brain malformations, intellectual disability, delayed motor development and visual problems. It is extremely rare. Type C3 is the mildest form and is also very rare. Onset is in early childhood and is characterized by a progressive muscle wasting, weakness and fatigue. Joint contractures and spinal deformities are present. To date, very few patients have been reported with type B3 and type C3 disease. Therefore, it may not be possible to predict the severity of the disease based on the genotype.
For information about carrier frequency and residual risk, please see the residual risk table.