The exome is the sum of all regions in the genome comprised of exons. The term exon was derived from “EXpressed regiON,” since these are the regions that get translated, as opposed to the intron, or “INTRagenic regiON” which is not represented in the final protein. Exome sequencing is a capture based method developed to identify variants in the coding region of genes that havea wide range of applications, including population genetics, genetic disease, and cancer studies. In 2001 human genome project required more than 200 scientists working for more than a decade with almost $3 billion cost while today, sequencing a whole genome is done over a period of a few days and is soon projected to cost less than $10 000. Human genome comprises about 3×109 bases, and contains approximately 180,000 coding regions (exome), constituting about 1.7% of a human genome. It is estimated that 85% of the disease (both Mendelian and common diseases such as cancer and diabetes) causing mutations occur in the coding and functional regions of the genome. For this reason, sequencing of the whole exome has the potential to uncover higher yield of relevant variants at far lower cost making it a cost-effective alternative to whole genome sequencing.
Authors: Deepak Agarwal1*, A. K. Singh1,Bhartendu Vimal1, Adnan Gora2, Shubham Varshney3
*1CoFS, BAU, Ranchi; 2CMFRI, Kochi; 3CIFE, Mumbai