The Rise and Rise of Exome Sequencing

Beginning in 2009, the advent of exome sequencing has contributed significantly towards new discoveries of heritable germline mutations and de novo mutations for rare Mendelian disorders with hitherto unknown genetic aetiologies. Exome sequencing is an efficient tool to identify disease mutations without the need of a multi-generational pedigree. Sequencing a single proband or multiple affected individuals has been shown to be successful in identifying disease mutations, but parents would be required in the case of de novo mutations. In addition to heritable germline and de novo mutations, exome sequencing has also succeeded in unravelling somatic driver mutations for a wide range of cancers through individual studies or international collaborative effort such as the Cancer Genome International Consortium. By contrast, the application of exome sequencing in complex diseases is relatively limited; probably it would be too expensive were it applied to thousands of samples to achieve the statistical power for rare or low frequency variants (<1%). On top of research discoveries, the application of exome sequencing as a diagnostic tool is also increasingly evident. In this article, we summarize and discuss the progress that has been made in these areas during almost a decade.