A comprehensive strategy for exome-based preconception carrier screening

Whole-exome sequencing (WES) provides the possibility of genome-wide preconception carrier screening (PCS). Here, we propose a filter strategy to rapidly identify the majority of relevant pathogenic mutations.

Our strategy was developed using WES data from eight consanguineous and five fictive nonconsanguineous couples and was subsequently applied to 20 other fictive nonconsanguineous couples. Presumably pathogenic variants based on frequency and database annotations or generic characteristics and mutation type were selected in genes shared by the couple and in the female's X-chromosome. Unclassified variants were not included.

This yielded an average of 29 (19-51) variants in genes shared by the consanguineous couples and 15 (6-30) shared by the nonconsanguineous couples. For X-linked variants, the numbers per female were 3 (1-5) and 1 (0-3), respectively. Remaining variants were verified manually. The majority were able to be quickly discarded, effectively leaving true pathogenic variants.

We conclude that WES is applicable for PCS, both for consanguineous and nonconsanguineous couples, with the remaining number of variants being manageable in a clinical setting. The addition of gene panels for filtering was not favorable because it resulted in missing pathogenic variants. It is important to develop and continuously curate databases with pathogenic mutations to further increase the sensitivity of WES-based PCS.Genet Med advance online publication 27 October 2016.