Compared to the high cost and


relative slow throughput during the initial sequencing of the human genome, researchers can now sequence at 30x coverage for $20,000 (consumables cost) in a matter of days using Next Generation Sequencing (NGS) platforms. In this approach, DNA templates are read randomly along the entire genome. This is accomplished by breaking the entire genome into small pieces, then ligating those small pieces of DNA to designated adapters for random read during DNA synthesis (sequencing-by- synthesis). Although NGS technology is very powerful, using this method requires a substantial investment in high- end equipment and high-level staff with expertise in data handling and analysis. Hence, the combined approach of genome wide association studies with NGS technologies is anticipated to result in the identification of highly significant gene variants associated with monogenic Mendelian disease characters. An alternative approach involves the


targeted resequencing of all protein- coding subsequences (that is, the exome), which requires <2% of the sequencing coverage required for the whole human genome and has been recently shown to be successful in identifying several Mendelian disorders. In contrast to the laborious approach of SNP homozygosity mapping and hence the requirement for consanguineous families, the exome capture approach is much faster and


“The first seeds of molecular analysis were provided in the early days of recombinant DNA technology”


does not require homozygosity mapping. Instead, its success relies on mutation being present in the captured portion of the genome and the mutation being identified as pathogenic within the many thousands of new variants identified each time an exome is sequenced.


FUTURE PERSPECTIVE It is highly anticipated that future human genome research will result in spectacular advances in our understanding of how the genome works, how disease works, and how genomic changes are associated with disease. A recent road map published by the Maryland-based National Human Genome Research Institute (NHGRI) illustrated the future course of genomic sciences according to the following:  Understanding the biology of genomes through the development of more comprehensive catalogues of data, the implementation of new research tools, and the continued acquisition of basic knowledge about genome structure and function in order to illuminate the complexity of genome biology


 Understanding the biology of disease by analyzing the normal and disease-related functions of the genetic and epigenetic contributors to disease, and the cellular pathways and biological processes in which they are involved, as important prerequisites for the development of improved strategies for diagnosis, prevention and therapeutic intervention  Advance the science of medicine by integrating genomic information as a standard practice in healthcare  Improving the effectiveness of healthcare through the clinical deployment of genomics. However, the success of this process depends on various factors including the development of viable electronic medical/ health record systems, demonstration of the effectiveness of the widespread adoption of genomic medicine, education of healthcare professionals, patients, and the public, and accessibility to the benefits that genomic research engenders. In the Arab world, there are ongoing


efforts to complete sequencing genomes of Arab individuals. Such projects attract a lot of attention especially due to the high levels of genetic diversity and the disproportionately high level of genetic disease in the region. The high levels of genetic disease will continue to provide plenty of fodder for rare disease gene hunters using GWAS and exome sequencing and the genetic diversity may help to narrow down causative variants for some common diseases. Yet, local healthcare systems may remain impermeable to the applications of genomic medicine as long as genomic research in the region maintains a profile very much below the threshold required for a substantial change. ■


ML


 REFERENCES References available on request (magazine@informa.com)


LEARN MORE


The Molecular Diagnosis track at the Medlab Congress is taking place on January 25th


. The Medlab Congress, part of


the Arab Health Exhibition & Conference, will be held at the Dubai Trade Centre from 23-26th of January 2012. To register your place as a delegate, and find out more information about all the Medlab conference streams, visit the website www.arabhealthonline.com and click on the Medlab tab.


26 www.lifesciencesmagazines.com


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