title: An SNX10 mutation causes malignant osteopetrosis of infancy.
abstract: BACKGROUND
  Osteopetrosis is a life-threatening, rare disorder typically resulting from osteoclast dysfunction and infrequently from failure to commitment to osteoclast lineage. Patients commonly present in infancy with macrocephaly, feeding difficulties, evolving blindness and deafness, and bone marrow failure. In ∼70% of the patients there is a molecularly defined failure to maintain an acid pH at the osteoclast-bone interface (the ruffled border) which is necessary for the bone resorptive activity.
  
  
  RESULTS
  In eight patients with infantile osteopetrosis which could be cured by bone marrow transplantation, the study identified by homozygosity mapping in distantly related consanguineous pedigrees a missense mutation in a highly conserved residue in the SNX10 gene. The mutation segregated with the disease in the families and was carried by one of 211 anonymous individuals of the same ethnicity. In the patients' osteoclasts, the mutant SNX10 protein was abnormally abundant and its distribution altered. The patients' osteoclasts were fewer and smaller than control cells, their resorptive capacity was markedly deranged, and the endosomal pathway was perturbed as evidenced by the distribution of internalised dextran.
  
  
  CONCLUSIONS
  SNX10 was recently shown to interact with vacuolar type H(+)-ATPase (V-ATPase) which pumps protons at the osteoclast-bone interface. Mutations in TCIRG1, the gene encoding a subunit of the V-ATPase complex, account for the majority of cases of osteopetrosis. It is speculated that SNX10 is responsible for the vesicular sorting of V-ATPase from Golgi or for its targeting to the ruffled border. A mutation in SNX10 may therefore result in 'secondary V-ATPase deficiency' with a failure to acidify the resorption lacuna. Determination of the sequence of the SNX10 gene is warranted in molecularly undefined patients with recessive 'pure' osteopetrosis of infancy.
authors.affiliation: Monique and Jacques Roboh Department of GeneticResearch, Hadassah, Hebrew University Medical Center, Jerusalem, Israel.
authors.forename: Memet
authors.initials: M
authors.lastname: Aker
authors.forename: Alex
authors.initials: A
authors.lastname: Rouvinski
authors.forename: Saar
authors.initials: S
authors.lastname: Hashavia
authors.forename: Asaf
authors.initials: A
authors.lastname: Ta-Shma
authors.forename: Avraham
authors.initials: A
authors.lastname: Shaag
authors.forename: Shamir
authors.initials: S
authors.lastname: Zenvirt
authors.forename: Shoshana
authors.initials: S
authors.lastname: Israel
authors.forename: Michael
authors.initials: M
authors.lastname: Weintraub
authors.forename: Albert
authors.initials: A
authors.lastname: Taraboulos
authors.forename: Zvi
authors.initials: Z
authors.lastname: Bar-Shavit
authors.forename: Orly
authors.initials: O
authors.lastname: Elpeleg
mesh_terms: D001483:Base Sequence; D003241:Consanguinity; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009154:Mutation; D010010:Osteoclasts / Q000378:metabolism / Q000473:pathology; D010022:Osteopetrosis / Q000235:genetics* / Q000473:pathology; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide; D058305:Sorting Nexins / Q000235:genetics*
chemical_list: C516568:SNX10 protein, human; D058305:Sorting Nexins