Familial Hemophagocytic Lymphohistiocytosis Type 5 (FHL-5) Is Caused by Mutations in Munc18-2 and Impaired Binding to Syntaxin 11

• Published in: American journal of human genetics Vol. 85; no. 4; pp. 482 - 492
• Main Authors: zur Stadt, Udo, Rohr, Jan, Seifert, Wenke, Koch, Florian, Grieve, Samantha, Pagel, Julia, Strauß, Julia, Kasper, Brigitte, Nürnberg, Gudrun, Becker, Christian, Maul-Pavicic, Andrea, Beutel, Karin, Janka, Gritta, Griffiths, Gillian, Ehl, Stephan, Hennies, Hans Christian
• Format: Journal Article
• Language: English
• Published: Cambridge, MA Elsevier Inc 09.10.2009; Cell Press; Elsevier
• Subjects: Binding sites; Biological and medical sciences; Child, Preschool; Chromosome Mapping; Chromosomes, Human, Pair 19; Exocytosis; Female; Fundamental and applied biological sciences. Psychology; General aspects. Genetic counseling; Genetic disorders; Genetics of eukaryotes. Biological and molecular evolution; Genotype; Genotype & phenotype; Humans; Infant; Lymphocytes; Lymphohistiocytosis, Hemophagocytic - genetics; Lymphohistiocytosis, Hemophagocytic - pathology; Male; Medical genetics; Medical sciences; Molecular and cellular biology; Munc18 Proteins - genetics; Munc18 Proteins - metabolism; Mutation; Polymorphism, Single Nucleotide; Proteins; Qa-SNARE Proteins - genetics; Qa-SNARE Proteins - metabolism; SNARE Proteins - metabolism; Saudi Arabia; Central Europe; Turkey; Human; Immunopathology; Hemophagocytic lymphohistiocytosis; Genetics; Mutation; Family study
• ISSN: 0002-9297; 1537-6605
• DOI: 10.1016/j.ajhg.2009.09.005

Rapid intracellular transport and secretion of cytotoxic granules through the immunological synapse requires a balanced interaction of several proteins. Disturbance of this highly regulated process underlies familial hemophagocytic lymphohistiocytosis (FHL), a genetically heterogeneous autosomal-recessive disorder characterized by a severe hyperinflammatory phenotype. Here, we have assigned FHL-5 to a 1 Mb region on chromosome 19p by using high-resolution SNP genotyping in eight unrelated FHL patients from consanguineous families. Subsequently, we found nine different mutations, either truncating or missense, in STXBP2 in twelve patients from Turkey, Saudi Arabia, and Central Europe. STXBP2 encodes syntaxin binding protein 2 (Munc18-2), involved in the regulation of vesicle transport to the plasma membrane. We have identified syntaxin 11, a SNARE protein mutated in FHL-4, as an interaction partner of STXBP2. This interaction is eliminated by the missense mutations found in our FHL-5 patients, which leads to a decreased stability of both proteins, as shown in patient lymphocytes. Activity of natural killer and cytotoxic T cells was markedly reduced or absent, as determined by CD107 degranulation. Our findings thus identify a key role for STXBP2 in lytic granule exocytosis.