Premarital and preconception genetic counseling are very important in highly consanguineous populations. In many traditional Arab societies, family-oriented genetic counseling offers an excellent approach in the prevention of genetic disorders. In most of the Arab countries, many of the towns and villages are, in effect, closed communities, in which the residents mainly marry within their own community. Within each town or village there can be at least one, and often more, autosomal recessive disease(s) that is/are exclusive to the residents of that specific location. Identifying the molecular basis of these diseases can enable genetic counseling and genetic screening, and therefore may greatly reduce the number of affected infants born. Methods used to identify the genes responsible for causing specific diseases include sequencing of specific genes, linkage analysis, homozygosity mapping and exome sequencing. Homozygosity mapping aims to identify the candidate region in which the causative gene is situated. Next generation sequencing techniques include exome sequencing; this focuses on only the protein-coding portion of the genome and is a powerful and costeffective method for elucidating the genetic basis of Mendelian disorders with hitherto unknown etiology. Once the causative gene for a specific disease has been identified, prenatal diagnosis by mutation testing in CVS or amniocytes can be carried out and termination of pregnancy offered in the case of an affected fetus. Preimplantation genetic diagnosis is described; this is a technique used to analyze embryos genetically before their transfer into the uterus in order to enable only unaffected embryos to be transferred.
Keywords: Autosomal recessive diseases, consanguineous populations, exome sequencing, genetic counseling, genetic screening, homozygosity mapping, linkage analysis, preimplantation genetic diagnosis, sequencing.