Trisomy 18 in Kuwait: a study of two decades

ABSTRACT

One hundred and eighteen patients with regular Trisomy 18 [T18] were ascertained clinically and cytogenetically in the Kuwait Medical Genetics Centre. The aim of this study was to provide an overview of T18 cases in Kuwait and highlight some associated factors, [out of the ascertained 118 T18 cases, 59 were delivered during the period 1994-1997]. The overall incidence rate during the years 1994 to 1997 was 9/10,000 livebirths [95% confidence interval 6.7 to 11.2 per 10,000 livebirths], which is considered high. The malefemale ratio among T18 cases was 12.1. To investigate the factors associated with T18, a group-matched case-control study was undertaken which included 131 normal healthy controls. The mean maternal age of the T18 patients' mothers [31.9 years] was significantly higher [p=0.002] than the controls' mean maternal age [27.1 years]. Abnormal presentation was recorded in 14.4% in T18 cases compared to 5.4% in controls, while the mode of delivery was abnormal in 43.2% of cases [90% of them were cesarean section] compared to 15.3% in controls, [p<0.001]. Polyhydramnios occurred in 9.3% of the T18 cases versus 1.5% in controls, [p<0.001]. Significant seasonal variation in T18 cases was detected with a peak in spring [March-May], [p<0.05]. The most common anomalies observed were congenital heart [38.1%], gastrointestinal malformations [25.4%], limb anomalies [24.6%], microcephaly [20.3%], omphalocele [11%], eye anomalies 11% and genital anomalies [9.3%]. Multiplicity of malformations was noticed [24.6% had only one malformation, 24.6% had two malformations, 17.8% had 3 malformations and 9.3% had 4 malformations]. In conclusion, the T18 incidence rate in Kuwait is high with possible associated factors of advanced parental age, polyhydramnios, abnormal presentation and mode of delivery