Consanguinity and dysmorphology in Arabs.

Incidence rates of congenital disorders among the 350 million inhabitants of Arab countries could be influenced via the people's demographic and cultural characteristics. Arabs usually marry at a young age and have large families. They share certain core cultural values and beliefs, with the family accepted as the central structure of society. Consanguineous marriage is favored and respected in most if not all Arab communities, and intrafamilial unions currently account for 20-50% of all marriages. First-cousin unions are especially popular and constitute almost one quarter of all marriages in many Arab countries. Consequently, autosomal recessive (AR) dysmorphic syndromes constitute a considerable proportion of all birth defects among Arabs. Arab geneticists, with their persistent commitment to advancing research, have contributed to the description of a number of rare and new AR syndromes with the identification of novel genes. The collaboration with research teams in high-income countries resulted in a plethora of data on pathogenic variants and their function in causing dysmorphic syndromes. There could still be a considerable number of rare dysmorphic syndromes that prevail among Arabs which are not hitherto described and whose underlying molecular pathologies are not yet defined. Arab countries should thus strive to deploy DNA diagnostics and to build research capability around local priorities. Furthermore, a characterization of the prevailing genetic disorders in each geographic location, together with their mutations, is needed to plan for appropriate screening and testing protocols. An overview of consanguinity in Arab countries and examples of dysmorphology syndromes associated with consanguinity with their available molecular bases will be discussed.