What are the genetic changes related to juvenile idiopathic arthritis ?
Juvenile idiopathic arthritis is thought to arise from a combination of genetic and environmental factors. The term "idiopathic" indicates that the specific cause of the disorder is unknown. Its signs and symptoms result from excessive inflammation in and around the joints. Inflammation occurs when the immune system sends signaling molecules and white blood cells to a site of injury or disease to fight microbial invaders and facilitate tissue repair. Normally, the body stops the inflammatory response after healing is complete to prevent damage to its own cells and tissues. In people with juvenile idiopathic arthritis, the inflammatory response is prolonged, particularly during movement of the joints. The reasons for this excessive inflammatory response are unclear.  Researchers have identified changes in several genes that may influence the risk of developing juvenile idiopathic arthritis. Many of these genes belong to a family of genes that provide instructions for making a group of related proteins called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders (such as viruses and bacteria). Each HLA gene has many different normal variations, allowing each person's immune system to react to a wide range of foreign proteins. Certain normal variations of several HLA genes seem to affect the risk of developing juvenile idiopathic arthritis, and the specific type of the condition that a person may have.  Normal variations in several other genes have also been associated with juvenile idiopathic arthritis. Many of these genes are thought to play roles in immune system function. Additional unknown genetic influences and environmental factors, such as infection and other issues that affect immune health, are also likely to influence a person's chances of developing this complex disorder.