What are the genetic changes related to Fukuyama congenital muscular dystrophy ?
Fukuyama congenital muscular dystrophy is caused by mutations in the FKTN gene. This gene provides instructions for making a protein called fukutin. Although the exact function of fukutin is unclear, researchers predict that it may chemically modify a protein called alpha ()-dystroglycan. This protein anchors cells to the lattice of proteins and other molecules (the extracellular matrix) that surrounds them. In skeletal muscles, -dystroglycan helps stabilize and protect muscle fibers. In the brain, this protein helps direct the movement (migration) of nerve cells (neurons) during early development.  The most common mutation in the FKTN gene reduces the amount of fukutin produced within cells. A shortage of fukutin likely prevents the normal modification of -dystroglycan, which disrupts that protein's normal function. Without functional -dystroglycan to stabilize muscle cells, muscle fibers become damaged as they repeatedly contract and relax with use. The damaged fibers weaken and die over time, leading to progressive weakness and atrophy of the skeletal muscles.  Defective -dystroglycan also affects the migration of neurons during the early development of the brain. Instead of stopping when they reach their intended destinations, some neurons migrate past the surface of the brain into the fluid-filled space that surrounds it. Researchers believe that this problem with neuronal migration causes cobblestone lissencephaly in children with Fukuyama congenital muscular dystrophy. Less is known about the effects of FKTN mutations in other parts of the body.  Because Fukuyama congenital muscular dystrophy involves a malfunction of -dystroglycan, this condition is described as a dystroglycanopathy.