title: Enamel defects and salivary methylmalonate in methylmalonic acidemia.
abstract: OBJECTIVE
  To characterize enamel defects in patients with methylmalonic acidemia (MMA) and cobalamin (cbl) metabolic disorders and to examine salivary methylmalonate levels in MMA.
  
  
  METHODS
  Teeth from patients (n = 32) were evaluated for enamel defects and compared with age- and gender-matched controls (n = 55). Complementation class (mut, cblA, cblB and cblC) and serum methylmalonate levels were examined. Primary teeth from two patients were examined by light and scanning electron microscopy and salivary methylmalonate levels from two patients were analyzed.
  
  
  RESULTS
  Enamel defects were significantly more prevalent per tooth in the affected group than the control group, across complementation types (P < 0.0001). The mut MMA subgroup had a significantly higher prevalence per individual of severe enamel defects than controls (P = 0.021), and those with enamel defects exhibited higher serum methylmalonate levels than those without (P = 0.017). Salivary methylmalonate levels were extremely elevated and were significantly higher than controls (P = 0.002). Primary teeth were free of enamel defects except for two cblC patients who exhibited severe enamel hypoplasia. One primary tooth from a cblC patient manifested markedly altered crystal microstructure.
  
  
  CONCLUSIONS
  Enamel anomalies represent a phenotypic manifestation of MMA and cbl metabolic disorders. These findings suggest an association between enamel developmental pathology and disordered metabolism.
authors.affiliation: National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-1851, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Bassim
authors.forename: J T
authors.initials: JT
authors.lastname: Wright
authors.forename: J P
authors.initials: JP
authors.lastname: Guadagnini
authors.forename: R
authors.initials: R
authors.lastname: Muralidharan
authors.forename: J
authors.initials: J
authors.lastname: Sloan
authors.forename: D L
authors.initials: DL
authors.lastname: Domingo
authors.forename: C P
authors.initials: CP
authors.lastname: Venditti
authors.forename: T C
authors.initials: TC
authors.lastname: Hart
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D002648:Child; D003743:Dental Enamel / Q000002:abnormalities* / Q000648:ultrastructure; D019229:Dentition, Permanent; D005260:Female; D005816:Genetic Complementation Test; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D008661:Metabolism, Inborn Errors / Q000145:classification / Q000150:complications* / Q000378:metabolism; D008764:Methylmalonic Acid / Q000378:metabolism*; D012016:Reference Values; D012463:Saliva / Q000378:metabolism; D018709:Statistics, Nonparametric; D014071:Tooth Abnormalities / Q000150:complications / Q000378:metabolism*; D014094:Tooth, Deciduous; D014805:Vitamin B 12 / Q000378:metabolism*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D008764:Methylmalonic Acid; D014805:Vitamin B 12