title: Segregation analysis of mandibular prognathism in Korean orthognathic surgery patients and their families.
abstract: OBJECTIVE
  To investigate the existence of genetic influences on the incidence of mandibular prognathism (MP) in Korean Class III patients.
  
  
  METHODS
  The probands consisted of 100 Class III patients with MP (51 men and 49 women; mean age, 22.1 ± 5.2 years; SNA, 81.2° ± 3.2°; SNB, 84.1° ± 3.9°) who underwent orthognathic surgery. Using three-generation pedigree charts, questionnaires, and clinical examinations, general information and information regarding MP for a total of 3777 relatives of the probands (1911 men and 1866 women) was ascertained. Familial correlations of MP between possible pairs in the pedigree were estimated. Heritability (h(2)) of MP under various models was estimated. Segregation analysis was conducted under the assumption of the nonpolygenic multivariate logistic model and finite polygenic mixed model. One-, two-, and three-susceptibility-type models were evaluated.
  
  
  RESULTS
  Among 3777 relatives, 199 (97 men and 102 women) were affected with MP (5.3%). Correlation coefficients of MP incidence in full siblings and in parent-offspring were .2003 and .2036, respectively (all P < .001). The h(2) of MP was estimated as 21.5% after adjusting for sex and founder effects. Two- and three-susceptibility-type models showed that the general model fit better than the other models. MP incidence did not have a major gene transmission model and was influenced by numerous minor effect genes and their additive effects.
  
  
  CONCLUSIONS
  These results suggest that the inherited susceptibility to MP in Korean Class III patients might be due to the summation of minor effects from a variety of different genes and/or influence of environmental factors, rather than Mendelian transmission of major genes.
authors.affiliation: a  Resident, Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Jeong-Min
authors.initials: JM
authors.lastname: Ko
authors.forename: Young Ju
authors.initials: YJ
authors.lastname: Suh
authors.forename: Jongrak
authors.initials: J
authors.lastname: Hong
authors.forename: Jun-Young
authors.initials: JY
authors.lastname: Paeng
authors.forename: Seung-Hak
authors.initials: SH
authors.lastname: Baek
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D044466:Asian People; D002508:Cephalometry; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008313:Malocclusion, Angle Class III / Q000453:epidemiology / Q000235:genetics*; D008962:Models, Theoretical; D010375:Pedigree; D011378:Prognathism / Q000453:epidemiology / Q000235:genetics*; D056910:Republic of Korea / Q000453:epidemiology