FEATURE GENETICS
explained by the exposure to common environmental factors, dietary traditions, and consanguineous marriages. To be able to clarify these correlations, however, the molecular etiologies of these disorders need to be very well understood in the region. Unfortunately, many indicators still reflect a dominance of clinical observations over molecular analyses in most of the research conducted in the region. A recent survey conducted by the Centre for Arab Genomic Studies on articles discussing genetic disorders in Arab patients indicate that gene-pathology articles constitute only 28% of the total number of articles analyzed (see figure 1). Yet, indications do demonstrate that a slow improvement in this situation is taking place. This is best expressed in the ratio of gene: disease records in the CTGA Database that increased from 0.36:1, to 0.38:1, and to 0.39:1 for years 2006, 2008, and 2010, respectively.
GENOME WIDE ASSOCIATION STUDIES The creation of the human genome reference sequence, including the location of genes, gene structure, and the location of common variants, allowed a relatively
“During the last 10 years, nearly 71 studies were aimed at the identification of multiple Arab families with genetic disorders”
quick transition from the ‘candidate gene approach’ to the more common ‘genome-wide approach’ to identify disease-producing mutations. In year 2001, tools to perform genome-wide association studies (GWAS) were introduced from the RIKEN institute in Japan. Since then, this method was utilized in hundreds of research studies as an important tool for the identification of the genes for polygenic diseases and drug responses. Research to depict genome-wide
associations for many disorders in Arabs is no exception. During the last 10 years, nearly 71 studies aimed at the identification of multiple Arab families with genetic disorders, the implementation of linkage analyses to identify associated gene loci, and the
characterization of candidate genes within the linked region followed by sequencing of these genes for putative causative mutations (see figure 2). These studies provided a wealth of information by linking genes to phenotypes and helped a great deal in global genome annotation efforts. In spite of that, the CTGA Database indicates that there are more than 250 genetic disorders described in Arab people that have not been genetically mapped thus far. Efforts to decipher the molecular pathologies of these disorders will definitely result in high value knowledge base.
CURRENT METHODS OF HUMAN GENOME RESEARCH At the time of the Human Genome Project, investigators waited with great anticipation for the first complete human genome reference sequence, which was mostly finished in 2003, at a cost of just under $3 billion. Today, new sequencing technologies allow us to sequence the complete human genome in a matter of days, and investigators will soon be able to sequence hundreds of individuals for their own individual research projects at costs that are within the budget of a typical research grant.
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