The POMT1 gene provides instructions for making one piece of the protein O-mannosyltransferase (POMT) enzyme complex. The other piece is produced from the POMT2 gene. This enzyme complex is present in many different tissues in the body but is particularly abundant in the muscles used for movement (skeletal muscles), fetal brain, and testes.~The POMT complex helps modify a protein called alpha (α)-dystroglycan. Specifically, this complex adds a sugar molecule called mannose to α-dystroglycan through a process called glycosylation. Glycosylation is critical for the normal function of α-dystroglycan.~The α-dystroglycan protein helps anchor the structural framework inside each cell (cytoskeleton) to the lattice of proteins and other molecules outside the cell (extracellular matrix). In skeletal muscles, glycosylated α-dystroglycan helps stabilize and protect muscle fibers. In the brain, it helps direct the movement (migration) of nerve cells (neurons) during early development.