title: The aetiology of hypodontia: the prevalence, severity and location of hypodontia within families.
abstract: OBJECTIVE
  Previous studies have indicated that hypodontia has a significantly higher prevalence in the relatives of affected individuals than in the general population. This study aims to examine further the roles of genetic and environmental factors in the aetiology of hypodontia by investigating the relationship between the severity and distribution of hypodontia between family members, and any discernable effect of maternal health during pregnancy and birth weight.
  
  
  RESULTS
  117 first degree relatives of 41 index patients were examined clinically and radiographically to identify the presence, severity and location of hypodontia. Both siblings and parents of index patients had a higher prevalence of hypodontia than the general population. The number and location of missing teeth was not related to the number and location of missing teeth in parents or siblings. The expression of hypodontia within a family was not affected by maternal health during pregnancy.
  
  
  CONCLUSIONS
  The variation found in the expression of hypodontia within families suggests that its occurrence is not solely determined by genetic factors, but epigenetic and environmental factors probably also are important. This finding is consistent with a multifactorial aetiology for this condition.
authors.affiliation: Department of Oral Health and Development, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield S10 2TA, UK.
authors.forename: N
authors.initials: N
authors.lastname: Parkin
authors.forename: C
authors.initials: C
authors.lastname: Elcock
authors.forename: R N
authors.initials: RN
authors.lastname: Smith
authors.forename: R C
authors.initials: RC
authors.lastname: Griffin
authors.forename: A H
authors.initials: AH
authors.lastname: Brook
mesh_terms: D000848:Anodontia / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D004777:Environment; D044127:Epigenesis, Genetic; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D010641:Phenotype; D011247:Pregnancy; D015995:Prevalence; D011859:Radiography; D012307:Risk Factors; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D006113:United Kingdom / Q000453:epidemiology