Whole Exome sequencing
Genomic DNA was extracted from whole blood for all patients at the time of evaluation and treatment at the fertility centre. Parental DNA was obtained from saliva using the Oragene OG-500 kit (DNA Genotek, Ottawa, Canada). Exomes of patient-parent trios were prepared for sequencing using 1 µg of high-quality genomic DNA, which was quantified with the Qubit dsDNA HS kit (Thermo Fisher Scientific, Waltham, MA, USA). Whole exome enrichment was performed using Illumina’s Nextera DNA Exome Capture kit (Illumina, San Diego, CA, USA) or Twist Bioscience’s Twist Human Core Exome Kit, as per manufacturer protocols. Individual sample libraries were then indexed with Illumina Nextera DNA UD indexes (Illumina, San Diego, CA, USA) prior to pooling libraries together. The final pooled library was sequenced on the NovaSeq 6000 platform (Illumina, San Diego, CA, USA) to an average coverage depth of 72X (Illumina Nextera kit) or 99X (Twist Bioscience’s kit).