A rare autosomal recessive disorder in which there is massive infiltration of several organs by activated lymphocytes and macrophages and anaemia caused by phagocytosis of erythrocytes. Type 1 is linked to chromosome 9 but the defective gene is not yet identified. In familial haemophagocytic lymphohistiocytosis type 2 (FHL2) there is a mutation in the gene encoding perforin. Type 3 is caused by mutation in the UNC13D gene, the product of which (1090 aa) is essential for the priming step of cytolytic granule secretion from cytotoxic T cells. Type 4 is caused by mutation in the syntaxin-11 gene.
Subjects: Medicine and Health.