title: Genetic variation in myosin 1H contributes to mandibular prognathism.
abstract: BACKGROUND
  Several candidate loci have been suggested as influencing mandibular prognathism (1p22.1, 1p22.2, 1p36, 3q26.2, 5p13-p12, 6q25, 11q22.2-q22.3, 12q23, 12q13.13, and 19p13.2). The goal of this study was to replicate these results in a well-characterized homogeneous sample set.
  
  
  METHODS
  Thirty-three single nucleotide polymorphisms spanning all candidate regions were studied in 44 prognathic and 35 Class I subjects from the University of Pittsburgh School of Dental Medicine Dental Registry and DNA Repository. The 44 subjects with mandibular prognathism had an average age of 18.4 years; 31 were female and 13 male; and 24 were white, 15 African American, 2 Hispanic, and 3 Asian. The 36 Class I subjects had an average age of 17.6 years; 27 were female and 9 male; and 27 were white, 6 African American, 1 Hispanic, and 2 Asian. Skeletal mandibular prognathism diagnosis included cephalometric values indicative of Class III such as an ANB smaller than 2°, a negative Wits appraisal, and a positive A-B plane. Additional mandibular prognathism criteria included negative overjet and visually prognathic (concave) profile as determined by the subject's clinical evaluation. Orthognathic subjects without jaw deformations were used as the comparison group. The mandibular prognathic and orthognathic subjects were matched by race, sex, and age. Genetic markers were tested by polymerase chain reaction with TaqMan chemistry. Chi-square and Fisher exact tests were used to determine overrepresentation of marker allele with an alpha of 0.05.
  
  
  RESULTS
  An association was unveiled between a marker in MYO1H (rs10850110) and the mandibular prognathism phenotype (P = 0.03). MYO1H is a Class I myosin that is in a different protein group than the myosin isoforms of muscle sarcomeres, which are the basis of skeletal muscle fiber typing. Class I myosins are necessary for cell motility, phagocytosis, and vesicle transport.
  
  
  CONCLUSIONS
  More strict clinical definitions might increase homogeneity and aid the studies of genetic susceptibility to malocclusions. We provide evidence that MYO1H can contribute to mandibular prognathism.
authors.affiliation: Department of Orthodontics, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Tassopoulou-Fishell
authors.forename: Kathleen
authors.initials: K
authors.lastname: Deeley
authors.forename: Erica M
authors.initials: EM
authors.lastname: Harvey
authors.forename: James
authors.initials: J
authors.lastname: Sciote
authors.forename: Alexandre R
authors.initials: AR
authors.lastname: Vieira
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000235:genetics; D001213:Asian / Q000235:genetics; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002648:Child; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008313:Malocclusion, Angle Class III / Q000235:genetics*; D008334:Mandible / Q000002:abnormalities*; D008875:Middle Aged; D024461:Myosin Type I / Q000235:genetics*; D010865:Pilot Projects; D020641:Polymorphism, Single Nucleotide; D011378:Prognathism / Q000235:genetics*; D044465:White People / Q000235:genetics; D055815:Young Adult
chemical_list: C569966:myosin 1H, human; D024461:Myosin Type I