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.
