Experience using singleton exome sequencing of probands as an approach to preconception carrier screening in consanguineous couples

Background Consanguineous couples have an increased risk of severe diseases in offspring due to autosomal recessive disorders. Exome sequencing (ES) offers the possibility of extensive preconception carrier screening (PCS) in consanguineous couples who may be at risk of rare genetic disorders. Methods We retrospectively analysed ES data from 65 probands affected with rare genetic disorders born from consanguineous couples. We explored diagnostic yield and carrier status for recessive disorders. Results The overall diagnostic yield in a singleton approach was 53.8%, mostly recessive variants. In a hypothetical exome-based PCS, only 11.7% of these causative rare variants would have been missed in the filtering process. Carrier screening for recessive conditions allowed the identification of at least one additional pathogenic or likely pathogenic variant in 85.7% of the probands, being the majority with a gene carrier frequency <1 in 200. In addition, considering only clinically actionable conditions, we estimated that 12.3% of our close consanguineous couples may be at risk for an additional recessive disease. Conclusions Our results demonstrate that ES outperforms panel-based screening in a PCS context in consanguineous couples and could potentially increase their reproductive autonomy and facilitate informed decision-making.