What are the genetic changes related to Mainzer-Saldino syndrome ?
Mainzer-Saldino syndrome is usually caused by mutations in the IFT140 gene. This gene provides instructions for making a protein that is involved in the formation and maintenance of cilia, which are microscopic, finger-like projections that stick out from the surface of cells and participate in signaling pathways that transmit information within and between cells. Cilia are important for the structure and function of many types of cells, including cells in the kidneys, liver, and brain. Light-sensing cells (photoreceptors) in the retina also contain cilia, which are essential for normal vision. Cilia also play a role in the development of the bones, although the mechanism is not well understood.  The movement of substances within cilia and similar structures called flagella is known as intraflagellar transport (IFT). This process is essential for the assembly and maintenance of these cell structures. During intraflagellar transport, cells use molecules called IFT particles to carry materials to and from the tips of cilia. IFT particles are made of proteins produced from related genes that belong to the IFT gene family. Each IFT particle is made up of two groups of IFT proteins: complex A, which includes at least six proteins, and complex B, which includes at least 15 proteins. The protein produced from the IFT140 gene forms part of IFT complex A (IFT-A).  Mutations in the IFT140 gene that cause Mainzer-Saldino syndrome may change the shape of the IFT140 protein or affect its interactions with other IFT proteins, likely impairing the assembly of IFT-A and the development or maintenance of cilia. As a result, fewer cilia may be present or functional, affecting many organs and tissues in the body and resulting in the signs and symptoms of Mainzer-Saldino syndrome. Disorders such as Mainzer-Saldino syndrome that are caused by problems with cilia and involve bone abnormalities are called skeletal ciliopathies.  While IFT140 gene mutations are believed to account for most cases of Mainzer-Saldino syndrome, mutations in additional genes that have not been identified may also cause this disorder.