Consanguineous marriages in Morocco and the consequence for the incidence of autosomal recessive disorders

Consanguineous marriage is traditionally common throughout Arab countries. This leads to an increased birth prevalence of infants with recessive disorders, congenital malformations, morbidity and mortality. The aim of this study was to evaluate the rate of consanguineous marriage in families with autosomal recessive diseases, and to compare it with the average rate of consanguinity in the Moroccan population. The study was conducted in the Department of Medical Genetics in Rabat on 176 families with autosomal recessive diseases diagnosed and confirmed by clinical, radiological, enzymatic or molecular investigations. The rate of consanguinity was also studied in 852 families who had infants with trisomy 21 confirmed by karyotyping. These families were chosen because: (i) there is no association between trisomy 21 and consanguinity, (ii) these cases are referred from different regions of Morocco and (iii) they concern all social statuses. Among 176 families with autosomal recessive disorders, consanguineous marriages comprised 59.09% of all marriages. The prevalence of consanguinity in Morocco was found to be 15.25% with a mean inbreeding coefficient of 0.0065. The differences in the rates of consanguineous marriages were highly significant when comparing the general population and couples with offspring affected by autosomal recessive conditions. These results place Morocco among the countries in the world with high rates of consanguinity. Autosomal recessive disorders are strongly associated with consanguinity. This study better defines the health risks associated with consanguinity for the development of genetic educational guidelines targeted at the public and the health sector. © 2009 Cambridge University Press.