What are the genetic changes related to Erdheim-Chester disease ?
More than half of people with Erdheim-Chester disease have a specific mutation in the BRAF gene. Mutations in other genes are also thought to be involved in this disorder.  The BRAF gene provides instructions for making a protein that helps transmit chemical signals from outside the cell to the cell's nucleus. This protein is part of a signaling pathway known as the RAS/MAPK pathway, which controls several important cell functions. Specifically, the RAS/MAPK pathway regulates the growth and division (proliferation) of cells, the process by which cells mature to carry out specific functions (differentiation), cell movement (migration), and the self-destruction of cells (apoptosis).  The BRAF gene mutation that causes Erdheim-Chester disease is somatic, which means that it occurs during a person's lifetime and is present only in certain cells. The mutation occurs in histiocytes or in immature precursor cells that will develop into histiocytes. This mutation leads to production of a BRAF protein that is abnormally active, which disrupts regulation of cell growth and division. The unregulated overproduction of histiocytes results in their accumulation in the body's tissues and organs, leading to the signs and symptoms of Erdheim-Chester disease.  The BRAF gene belongs to a class of genes known as oncogenes. When mutated, oncogenes have the potential to cause normal cells to become cancerous. Researchers disagree on whether Erdheim-Chester disease should be considered a form of cancer because of the unregulated accumulation of histiocytes.