Trisomy 18 in Kuwait.

BACKGROUND: Trisomy 18 (Edwards' syndrome, T18) is the second most common trisomy in man. We describe 118 children with regular T18 who were ascertained clinically and cytogenetically in the Kuwait Medical Genetics Centre during 1980-1997. METHODS: Ascertainment of T18 cases was performed shortly after birth. Chromosomal studies were carried out in addition to other relevant investigations. To investigate the factors associated with T18, a case-control study was carried out with 131 normal healthy newborns. Studied factors included maternal and paternal age, birth order, abortion, associated malformation, and survival. Multiple logistic regression analysis was used to adjust for confounding between variables. RESULTS: There was a preponderance of females among T18 cases (female:male ratio 2.1:1). The majority of T18 cases (53%) died before the second week of life. The most common associated anomalies were: congenital heart (38.1%) and gastrointestinal (25.4%). Multiplicity of malformations was also observed. Significant seasonal variation in T18 cases was detected with a peak in spring. Of the 118 T18 cases, 59 were delivered during 1994-1997 (average overall T18 birth prevalence rate 8.95 per 10 000 live births [95% CI: 6.66-11.23]). Concerning maternal age, 30.5% of the T18 cases' mothers were > or =35 years compared to 10.7% in the control group. The difference was statistically significant, P = 0.002. Logistic regression analysis showed that maternal age >30 years was a significant risk factor for T18, after adjusting for confounding with paternal age. Paternal age and abortion were not found to be significant risk factors. CONCLUSION: Trisomy 18 birth prevalence rate is high in Kuwait with advanced maternal age as a significant risk factor.

PIP: This paper describes associated factors of trisomy 18 (T18) or Edwards' syndrome among infants in Kuwait. A case control study of 131 normal newborn controls was undertaken. The study included information about gender, maternal age, paternal age, birth order, reproductive history, consanguinity, survival, and associated anomalies. Results showed a preponderance of females among T18 cases (female/male ratio, 2.1:1). The difference between the T18-case mothers and the control-group mothers was statistically significant (P = 0.002); however, there was no significant difference with regard to paternal age. The logistic regression analysis showed that the odds ratio for 2 abortions with reference to (0/1) abortion was 1.086, which is statistically significant as a risk for T18. The majority of children with T18 died before the second week of life. With regard to malformations, the most common associated anomalies were congenital heart and gastrointestinal abnormalities. Thus, the prevalence of T18 is high in Kuwait, with advanced maternal age as a significant risk factor.

Clustering of trisomy 18 in Kuwait: Genetic predisposition or environmental?

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. MATERIALS AND 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. CONCLUSION: 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.