What are the genetic changes related to spastic paraplegia type 15 ?
Mutations in the ZFYVE26 gene cause spastic paraplegia type 15. This gene provides instructions for making a protein called spastizin. This protein is important in a process called autophagy, in which worn-out cell parts and unneeded proteins are recycled within cells. Specifically, spastizin is involved in the formation and maturation of sacs called autophagosomes (or autophagic vacuoles) that transport unneeded materials to be broken down. Spastizin also plays a role in the process by which dividing cells separate from one another (cytokinesis).  Many ZFYVE26 gene mutations that cause spastic paraplegia type 15 result in a shortened spastizin protein that is quickly broken down. As a result, functional autophagosomes are not produced, autophagy cannot occur, and recycling of materials within cells is decreased. An inability to break down unneeded materials, and the subsequent accumulation of these materials in cells, leads to cell dysfunction and often cell death. The loss of cells in the brain and other parts of the body is responsible for many of the features of spastic paraplegia type 15.  It is unclear whether a lack of spastizin protein interferes with normal cytokinesis and whether impaired cell division contributes to the signs and symptoms of spastic paraplegia type 15.