Interest of exome sequencing trio‐like strategy based on pooled parental DNA for diagnosis and translational research in rare diseases

BACKGROUND: Exome sequencing (ES) has become the most powerful and cost‐effective molecular tool for deciphering rare diseases with a diagnostic yield approaching 30%–40% in solo‐ES and 50% in trio‐ES. We applied an innovative parental DNA pooling method to reduce the parental sequencing cost while maintaining the diagnostic yield of trio‐ES. METHODS: We pooled six (Agilent‐CRE‐v2–100X) or five parental DNA (TWIST‐HCE–70X) aiming to detect allelic balance around 8–10% for heterozygous status. The strategies were applied as second‐tier (74 individuals after negative solo‐ES) and first‐tier approaches (324 individuals without previous ES). RESULTS: The allelic balance of parental‐pool variants was around 8.97%. Sanger sequencing uncovered false positives in 1.5% of sporadic variants. In the second‐tier approach, we evaluated than two thirds of the Sanger validations performed after solo‐ES (41/59–69%) would have been saved if the parental‐pool segregations had been available from the start. The parental‐pool strategy identified a causative diagnosis in 18/74 individuals (24%) in the second‐tier and in 116/324 individuals (36%) in the first‐tier approaches, including 19 genes newly associated with human disorders. CONCLUSIONS: Parental‐pooling is an efficient alternative to trio‐ES. It provides rapid segregation and extension to translational research while reducing the cost of parental and Sanger sequencing.