Clinical exome sequencing – Norwegian findings.

Background: New DNA-sequencing technology is revolutionising medical diagnostics. Through the use of exome sequencing, it is now possible to sequence all human genes in parallel. This technology has been widely used in research over the last few years and is now also being applied to diagnostics. The aim of this study was to systematically examine initial experiences with diagnostic exome sequencing in Norway.

Material And Method: This is a retrospective observational study of the results of all exome sequencing performed by the Section of Medical Genetics at Telemark Hospital between December 2012 and October 2014, and includes 125 persons in 46 families. The majority of these families were being investigated for a syndrome (n = 35, 76%) or neurological disease (n = 9, 20%).

Results: Exome sequencing detected pathogenic sequence variants in 15 of 46 probands, and variants of unknown significance in 12 probands. Of the 100 patients who stated their wishes regarding feedback of any incidental findings, six indicated that they did not wish to receive such information. There were no incidental findings in this study, but neither were such sequence variants actively looked for.

Interpretation: Exome sequencing can enable more patients with syndromes or neurological diseases to receive a causal diagnosis, and to receive this diagnosis at an earlier stage. However, the patients in this study were quite highly selected, and the results must therefore be interpreted with caution.