Question: What is (are) familial hemophagocytic lymphohistiocytosis ?
Answer: Familial hemophagocytic lymphohistiocytosis is a disorder in which the immune system produces too many activated immune cells (lymphocytes) called T cells, natural killer cells, B cells, and macrophages (histiocytes). Excessive amounts of immune system proteins called cytokines are also produced. This overactivation of the immune system causes fever and damages the liver and spleen, resulting in enlargement of these organs. Familial hemophagocytic lymphohistiocytosis also destroys blood-producing cells in the bone marrow, a process called hemophagocytosis. As a result, affected individuals have low numbers of red blood cells (anemia) and a reduction in the number of blood cells involved in clotting (platelets). A reduction in platelets may cause easy bruising and abnormal bleeding. The brain may also be affected in familial hemophagocytic lymphohistiocytosis. As a result, affected individuals may experience irritability, delayed closure of the bones of the skull in infants, neck stiffness, abnormal muscle tone, impaired muscle coordination, paralysis, blindness, seizures, and coma. In addition to neurological problems, familial hemophagocytic lymphohistiocytosis can cause abnormalities of the heart, kidneys, and other organs and tissues. Affected individuals also have an increased risk of developing cancers of blood-forming cells (leukemia and lymphoma). Signs and symptoms of familial hemophagocytic lymphohistiocytosis usually become apparent during infancy, although occasionally they appear later in life. They usually occur when the immune system launches an exaggerated response to an infection, but may also occur in the absence of infection. Without treatment, most people with familial hemophagocytic lymphohistiocytosis survive only a few months.
Source: GHR

Question: How many people are affected by familial hemophagocytic lymphohistiocytosis ?
Answer: Familial hemophagocytic lymphohistiocytosis occurs in approximately 1 in 50,000 individuals worldwide.
Source: GHR

Question: What are the genetic changes related to familial hemophagocytic lymphohistiocytosis ?
Answer: 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.
Source: GHR

Question: What are the treatments for familial hemophagocytic lymphohistiocytosis ?
Answer: These resources address the diagnosis or management of familial hemophagocytic lymphohistiocytosis: - Gene Review: Gene Review: Hemophagocytic Lymphohistiocytosis, Familial - Genetic Testing Registry: Familial hemophagocytic lymphohistiocytosis - Genetic Testing Registry: Hemophagocytic lymphohistiocytosis, familial, 2 - Genetic Testing Registry: Hemophagocytic lymphohistiocytosis, familial, 3 - Genetic Testing Registry: Hemophagocytic lymphohistiocytosis, familial, 4 - Genetic Testing Registry: Hemophagocytic lymphohistiocytosis, familial, 5 - The Merck Manual for Healthcare Professionals - University of Minnesota: Pediatric Blood & Marrow Transplantation Center These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
Source: GHR