title: Effect of consanguinity on birth defects in Saudi women: results from a nested case-control study.
abstract: BACKGROUND
  The role of consanguinity in the etiology of structural birth defects outside of chromosomal and inherited disorders has always been debated. We studied the independent role of consanguinity on birth defects in Saudi women with a high prevalence of consanguineous marriages.
  
  
  METHODS
  This case and control study was nested within a 3-year prospective cohort study to examine patterns of fetal and neonatal malformations in Saudi women at Prince Sultan Military Medical City (PSMMC), Riyadh -Saudi Arabia. Consanguineous marriages were defined as marriages with first or second cousins (related); unions beyond second cousins (distant relatives) were considered unrelated for this study.
  
  
  RESULTS
  During the 3-year study (July 2010 through June 2013), there were 28,646 total births; of these, we included 1,179 babies with major birth defects, and 1,262 babies as their controls. The consanguinity prevalence for all included women was 49.6%. The consanguinity among babies with major Birth Defects (BDs) was 54.5% and 45.2% for controls (P < 0.0002). The prevalence of major birth defects was 41.1 per 1000 total births. Univariate analysis showed that consanguinity had a statistically significant contribution in babies born with genetic syndromes, isolated renal defects, and isolated other defects (P < 0.05). Multivariate logistic regression analyses showed that consanguinity was an independent risk factor for this high prevalence of birth defects in the study population (P < 0.0002).
  
  
  CONCLUSIONS
  The prevalence of major birth defects in the study population is higher than what is reported from European countries. Consanguinity is a significant independent risk factor for the high prevalence of birth defects.
authors.affiliation: Prince Sultan Military Medical City, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Muhammad Ali
authors.initials: MA
authors.lastname: Majeed-Saidan
authors.forename: Amer N
authors.initials: AN
authors.lastname: Ammari
authors.forename: Amal M
authors.initials: AM
authors.lastname: AlHashem
authors.forename: Maha S
authors.initials: MS
authors.lastname: Al Rakaf
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Shoukri
authors.forename: Ester
authors.initials: E
authors.lastname: Garne
authors.forename: Ahmed Mohammed
authors.initials: AM
authors.lastname: Kurdi
mesh_terms: D000015:Abnormalities, Multiple / Q000453:epidemiology* / Q000473:pathology; D000328:Adult; D016022:Case-Control Studies; D003241:Consanguinity; D005260:Female; D006330:Heart Defects, Congenital / Q000453:epidemiology* / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D009436:Neural Tube Defects / Q000453:epidemiology* / Q000473:pathology; D015995:Prevalence; D012307:Risk Factors; D012529:Saudi Arabia / Q000453:epidemiology; D014564:Urogenital Abnormalities / Q000453:epidemiology* / Q000473:pathology
keywords: birth defects; consanguineous marriages; consanguinity; first cousins; risk factors; second cousins