title: Clustering of trisomy 18 in Kuwait: Genetic predisposition or environmental?
abstract: BACKGROUND
  This study describes 59 newborns with regular trisomy 18 (EdwardsA centAA syndrome, T18) who were ascertained clinically and cytogenetically at the Kuwait Medical Genetic Centre from 1994 to 1997, out of 118 T18 cases identified from 1980 to 1997.
  
  
  METHODS
  T18 cases were ascertained clinically and cytogenetically shortly after birth. In addition to assessing the T18 birth prevalence rate and confidence limits during the years 1994-1997, we investigated the possible etiological factors by a case-control study with normal healthy newborns. Studied factors included gender, parental age, birth order, abortion, clinical variables (presentation, amniotic fluid and mode of delivery), and survival.
  
  
  RESULTS
  The average T18 birth prevalence rate during the period was 8.95 per 10,000 live births (95% confidence limits 6.66-11.23). The T18 cases were mostly females, with a male:female ratio of 1:2.1, and the majority (53%) died before the second week of life. Maternal age above 30 years was found to be a significant factor for T18.
  
  
  CONCLUSIONS
  This high T18 birth prevalence rate suggests clustering of T18 in the highly inbred population of Kuwait. Such clustering may indicate a possible environmental, and to a lesser extent, genetic predisposition to aneuploidy nondisjunction.
authors.affiliation: Kuwait Medical Genetic Centre, and Department of Community Medicine, Kuwait University, Kuwait.
authors.forename: K K
authors.initials: KK
authors.lastname: Naguib
authors.forename: S A
authors.initials: SA
authors.lastname: Al-Awadi
authors.forename: L
authors.initials: L
authors.lastname: Bastaki
authors.forename: M A
authors.initials: MA
authors.lastname: Moussa
authors.forename: S A
authors.initials: SA
authors.lastname: Abulhassan
authors.forename: S
authors.initials: S
authors.lastname: Tayel
authors.forename: K
authors.initials: K
authors.lastname: Murthy