title: NT5E mutations and arterial calcifications.
abstract: BACKGROUND
  Arterial calcifications are associated with increased cardiovascular risk, but the genetic basis of this association is unclear.
  
  
  METHODS
  We performed clinical, radiographic, and genetic studies in three families with symptomatic arterial calcifications. Single-nucleotide-polymorphism analysis, targeted gene sequencing, quantitative polymerase-chain-reaction assays, Western blotting, enzyme measurements, transduction rescue experiments, and in vitro calcification assays were performed.
  
  
  RESULTS
  We identified nine persons with calcifications of the lower-extremity arteries and hand and foot joint capsules: all five siblings in one family, three siblings in another, and one patient in a third family. Serum calcium, phosphate, and vitamin D levels were normal. Affected members of Family 1 shared a single 22.4-Mb region of homozygosity on chromosome 6 and had a homozygous nonsense mutation (c.662C→A, p.S221X) in NT5E, encoding CD73, which converts AMP to adenosine. Affected members of Family 2 had a homozygous missense mutation (c.1073G→A, p.C358Y) in NT5E. The proband of Family 3 was a compound heterozygote for c.662C→A and c.1609dupA (p.V537fsX7). All mutations found in the three families result in nonfunctional CD73. Cultured fibroblasts from affected members of Family 1 showed markedly reduced expression of NT5E messenger RNA, CD73 protein, and enzyme activity, as well as increased alkaline phosphatase levels and accumulated calcium phosphate crystals. Genetic rescue experiments normalized the CD73 and alkaline phosphatase activity in patients' cells, and adenosine treatment reduced the levels of alkaline phosphatase and calcification.
  
  
  CONCLUSIONS
  We identified mutations in NT5E in members of three families with symptomatic arterial and joint calcifications. This gene encodes CD73, which converts AMP to adenosine, supporting a role for this metabolic pathway in inhibiting ectopic tissue calcification. (Funded by the National Human Genome Research Institute and the National Heart, Lung, and Blood Institute of the National Institutes of Health.).
authors.affiliation: National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20892, USA.
authors.forename: Cynthia
authors.initials: C
authors.lastname: St Hilaire
authors.forename: Shira G
authors.initials: SG
authors.lastname: Ziegler
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Markello
authors.forename: Alfredo
authors.initials: A
authors.lastname: Brusco
authors.forename: Catherine
authors.initials: C
authors.lastname: Groden
authors.forename: Fred
authors.initials: F
authors.lastname: Gill
authors.forename: Hannah
authors.initials: H
authors.lastname: Carlson-Donohoe
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lederman
authors.forename: Marcus Y
authors.initials: MY
authors.lastname: Chen
authors.forename: Dan
authors.initials: D
authors.lastname: Yang
authors.forename: Michael P
authors.initials: MP
authors.lastname: Siegenthaler
authors.forename: Carlo
authors.initials: C
authors.lastname: Arduino
authors.forename: Cecilia
authors.initials: C
authors.lastname: Mancini
authors.forename: Bernard
authors.initials: B
authors.lastname: Freudenthal
authors.forename: Horia C
authors.initials: HC
authors.lastname: Stanescu
authors.forename: Anselm A
authors.initials: AA
authors.lastname: Zdebik
authors.forename: R Krishna
authors.initials: RK
authors.lastname: Chaganti
authors.forename: Robert L
authors.initials: RL
authors.lastname: Nussbaum
authors.forename: Robert
authors.initials: R
authors.lastname: Kleta
authors.forename: William A
authors.initials: WA
authors.lastname: Gahl
authors.forename: Manfred
authors.initials: M
authors.lastname: Boehm
mesh_terms: D015720:5'-Nucleotidase / Q000235:genetics* / Q000378:metabolism; D001158:Arteries / Q000473:pathology; D050197:Atherosclerosis / Q000235:genetics*; D002114:Calcinosis / Q000235:genetics*; D002896:Chromosomes, Human, Pair 6; D018389:Codon, Nonsense; D004252:DNA Mutational Analysis; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D005838:Genotype; D006801:Humans; D007383:Intermittent Claudication / Q000235:genetics; D007592:Joint Diseases / Q000235:genetics*; D035002:Lower Extremity / Q000098:blood supply / Q000000981:diagnostic imaging; D009154:Mutation; D020125:Mutation, Missense; D020641:Polymorphism, Single Nucleotide; D012333:RNA, Messenger / Q000378:metabolism; D011859:Radiography
chemical_list: D018389:Codon, Nonsense; D012333:RNA, Messenger; D015720:5'-Nucleotidase