The effect of consanguinity on congenital disabilities in the Kuwaiti population

Consanguinity has been shown to increase homozygosity and to reduce genetic variation in a group, which may protect against the expression of recessive genes that can lead to genetic disorders. Consanguineous marriages are practised widely in Kuwait. The major aim of this study is to delineate the association of consanguineous marriages with congenital disabilities in different Kuwaiti population subcultures. A total of 9104 married Kuwaiti females aged 15-79 years from different backgrounds were selected at ten primary health care centres from six governorates in Kuwait. Data were collected using a questionnaire and analysed with chi-squared tests. The data indicate significant differences in the occurrence of genetic diseases in consanguineous couples' offspring (4.88%) compared with those of non-consanguineous couples (4.13%) (p<0.002). The results also show significant differences in frequencies of genetic/environmental diseases in consanguineous couples' offspring (8.59%) compared with those of non-consanguineous couples (8.23%) (p<0.005). No significant differences between the two groups regarding environmental diseases were observed. A higher frequency of genetic diseases was found in first- (6.97%; p<0.001), second- (6.78%; p<0.001) and third-cousin (6.46%; p<0.022) couples' offspring compared with those of non-consanguineous couples. The frequency of congenital disabilities in the offspring of couples from consanguineous marriages (2.9%) is higher than that in the offspring of non-consanguineous marriages (2.3%). But this difference is not significant at the 0.05 level. First-cousin marriages have the highest frequency (3.5%) of congenital disabilities compared with other kinds of marriages (2.1-2.3%). Differences across groups are significant (p<0.036). Significant differences are found for first-cousin couples in both physical (2.37; p<0.042) and mental (0.74; p<0.037) disabilities compared with non-consanguineous couples. No significant differences were observed in deafness and blindness disabilities. The data show no significant differences between second- and third-cousin and non-consanguineous couples in physical, mental or deafness and blindness disabilities. There are no significant differences in the percentages of offspring with congenital disabilities in consanguineous and non-consanguineous marriages across sub-population groups for the total of four types of congenital disability.