What are the genetic changes related to mandibuloacral dysplasia ?
The two forms of mandibuloacral dysplasia are caused by mutations in different genes. Mutations in the LMNA gene cause MADA, and mutations in the ZMPSTE24 gene cause MADB. Within cells, these genes are involved in maintaining the structure of the nucleus and may play a role in many cellular processes.  The LMNA gene provides instructions for making two related proteins, lamin A and lamin C. These proteins act as scaffolding (supporting) components of the nuclear envelope, which is the membrane that surrounds the nucleus in cells. The nuclear envelope regulates the movement of molecules into and out of the nucleus and may help regulate the activity of certain genes. Mutations in this gene likely change the structure of lamin A and lamin C.  The lamin A protein (but not lamin C) must be processed within the cell before becoming part of the nuclear envelope. The protein produced from the ZMPSTE24 gene is involved in this processing; it cuts the immature lamin A protein (prelamin A) at a particular location, forming mature lamin A. Mutations in the ZMPSTE24 gene lead to a buildup of prelamin A and a shortage of the mature protein.  Mutations in the LMNA or ZMPSTE24 gene likely disrupt the structure of the nuclear envelope. Researchers are working to understand how these genetic changes result in the signs and symptoms of mandibuloacral dysplasia.