What are the genetic changes related to familial hemophagocytic lymphohistiocytosis ?
Familial hemophagocytic lymphohistiocytosis may be caused by mutations in any of several genes. These genes provide instructions for making proteins that help destroy or deactivate lymphocytes that are no longer needed. By controlling the number of activated lymphocytes, these genes help regulate immune system function.  Approximately 40 to 60 percent of cases of familial hemophagocytic lymphohistiocytosis are caused by mutations in the PRF1 or UNC13D genes. Smaller numbers of cases are caused by mutations in other known genes. In some affected individuals, the genetic cause of the disorder is unknown.  The gene mutations that cause familial hemophagocytic lymphohistiocytosis impair the body's ability to regulate the immune system. These changes result in the exaggerated immune response characteristic of this condition.