Description | Protein which, if defective, causes familial hemophagocytic lymphohistiocytosis. FHL is a genetically heterogeneous, autosomal recessive disorder characterized by immune dysregulation with hypercytokinemia and defective natural killer cell function. The clinical features of the disease include fever, hepatosplenomegaly, cytopenia, hypertriglyceridemia, hypofibrinogenemia, and neurological abnormalities ranging from irritability and hypotonia to seizures, cranial nerve deficits and ataxia. Hemophagocytosis is a prominent feature of the disease, and non-malignant infiltration of macrophages and activated T lymphocytes in lymph nodes, spleen and other organs is also found |