LARGE1 gene
The LARGE1 gene is critical for the glycosylation of alpha-dystroglycan, a process necessary for stabilizing muscle fibers and directing nerve cell migration.
Overview
The protein produced by the LARGE1 gene is located in the Golgi apparatus, where it performs a process called glycosylation. This involves adding sugar molecules to a protein called alpha (α)-dystroglycan. This modification is essential for the protein's function.
α-dystroglycan acts as an anchor, connecting the internal structural framework of a cell (the cytoskeleton) to the extracellular matrix outside the cell. In skeletal muscles, this connection stabilizes and protects muscle fibers. In the brain, it directs the migration of neurons during development.
Health Conditions Related to Genetic Changes
Walker-Warburg syndrome
Mutations in the LARGE1 gene can cause Walker-Warburg syndrome, the most severe form of congenital muscular dystrophy. This condition results in:
- Skeletal muscle weakness
- Brain abnormalities
- Eye abnormalities
These mutations prevent the normal glycosylation of α-dystroglycan, meaning it can no longer anchor cells effectively. Without this stabilization, muscle fibers are damaged during contraction and eventually die. Additionally, defective α-dystroglycan disrupts neuronal migration, leading to cobblestone lissencephaly, where the brain surface appears bumpy and irregular rather than having normal folds.
Congenital muscular dystrophy type 1D (MDC1D)
LARGE1 mutations are also involved in congenital muscular dystrophy type 1D (MDC1D). This is a less severe form of the disorder that causes muscle weakness, intellectual disability, and brain abnormalities, but typically does not affect the eyes.
Genomic Location
The LARGE1 gene is found on chromosome 22.
