What are the genetic changes related to Nakajo-Nishimura syndrome ?
Nakajo-Nishimura syndrome is caused by mutations in the PSMB8 gene. This gene provides instructions for making one part (subunit) of specialized cell structures called immunoproteasomes, which are found primarily in immune system cells. Immunoproteasomes play an important role in regulating the immune system's response to foreign invaders, such as viruses and bacteria. One of the primary functions of immunoproteasomes is to help the immune system distinguish the body's own proteins from proteins made by foreign invaders, so the immune system can respond appropriately to infection.  Mutations in the PSMB8 gene greatly reduce the amount of protein produced from the PSMB8 gene, which impairs the normal assembly of immunoproteasomes and causes the immune system to malfunction. For unknown reasons, the malfunctioning immune system triggers abnormal inflammation that can damage the body's own tissues and organs; as a result, Nakajo-Nishimura syndrome is classified as an autoinflammatory disorder.  Abnormal inflammation likely underlies many of the signs and symptoms of Nakajo-Nishimura syndrome, including the nodular erythema, recurrent fevers, joint problems, and hepatosplenomegaly. It is less clear how mutations in the PSMB8 gene lead to muscle wasting and lipodystrophy. Studies suggest that the protein produced from the PSMB8 gene may play a separate role in the maturation of fat cells (adipocytes), and a shortage of this protein may interfere with the normal development and function of these cells.