title: Issues involved in the phenotypic classification of orofacial clefts ascertained through a state birth defects registry for the North Carolina Cleft Outcomes Study.
abstract: BACKGROUND
  Epidemiologic studies involving birth defects are extremely sensitive to phenotype accuracy and precision. We devised a case review and classification protocol for a project to study school achievement in children with idiopathic, nonsyndromic orofacial clefts to improve the reliability of phenotypic classification from the statewide birth defects registry.
  
  
  METHODS
  Surveillance-program abstraction data and medical records at the birth or treating hospitals were used when available. Exclusion criteria included: median cleft lip; Tessier cleft; premaxillary agenesis; presence of a recognizable syndrome, phenotype, association, or sequence (other than Robin sequence); clefts with other malformations not considered to be normal or common variants in the newborn; and cases with documented or suspected genetic or teratogenic causes.
  
  
  RESULTS
  Of 712 children identified with orofacial clefts, 153 were excluded, leaving 559 nonsyndromic orofacial cleft cases of unknown cause in the final study. These cases were grouped into the following clinically meaningful types: cleft lip with or without cleft alveolus; cleft lip and cleft palate; and cleft palate only. This review and classification process resulted in the elimination of 21.5% of the original cohort of identified cases, with most exclusions being due to suspected syndromic associations.
  
  
  CONCLUSIONS
  Verbatim descriptions of the clinical findings are critical for accurate classification of diagnoses. This review process improved the precision of orofacial cleft phenotype classification for our study. Precision would have been further improved if all of the cases had verbatim descriptions of diagnoses and all medical records could have been reviewed by the classification team.
authors.affiliation: University of North Carolina at Chapel Hill (UNC-CH), Departments of Pediatrics and Genetics, Chapel Hill, North Carolina.
authors.forename: Arthur S
authors.initials: AS
authors.lastname: Aylsworth
authors.affiliation: Duke Children's Hospital and Health Center, Division of Plastic, Maxillofacial, & Oral Surgery, Durham, North Carolina.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Allori
authors.affiliation: UNC-CH School of Dentistry, Department of Dental Ecology, Chapel Hill, North Carolina.
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Pimenta
authors.affiliation: Duke Children's Hospital and Health Center, Division of Plastic, Maxillofacial, & Oral Surgery, Durham, North Carolina.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Marcus
authors.affiliation: North Carolina State Center for Health Statistics, North Carolina Birth Defects Monitoring Program, Raleigh, North Carolina.
authors.forename: Katherine G
authors.initials: KG
authors.lastname: Harmsen
authors.affiliation: UNC-CH, Center for Health Promotion and Disease Prevention, Chapel Hill, North Carolina.
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Watkins
authors.affiliation: UNC-CH, Center for Health Promotion and Disease Prevention, Chapel Hill, North Carolina.
authors.forename: Barry L
authors.initials: BL
authors.lastname: Ramsey
authors.affiliation: UNC-CH School of Dentistry, Department of Dental Ecology, Chapel Hill, North Carolina.
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Strauss
authors.affiliation: North Carolina State Center for Health Statistics, North Carolina Birth Defects Monitoring Program, Raleigh, North Carolina.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Meyer
mesh_terms: D001921:Brain / Q000002:abnormalities* / Q000473:pathology; D002648:Child; D002971:Cleft Lip / Q000145:classification* / Q000473:pathology*; D002972:Cleft Palate / Q000145:classification* / Q000473:pathology*; D000013:Congenital Abnormalities; D006801:Humans; D009657:North Carolina / Q000453:epidemiology; D012042:Registries / Q000706:statistics & numerical data*
keywords: birth defect; classification; cleft lip; cleft lip and palate; cleft palate; epidemiologic study; malformation; nonsyndromic; orofacial cleft