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Sperm_PacBio_CCS_sequencing

PacBio circular consensus sequencing (CCS) produces long reads with unparalleled base accuracy. Longer read length enables confident placement of reads to the reference genome and this allows nucleotide resolution detection of structural rearrangements. Our internal assessment of PacBio CCS base accuracy shows that PacBio CCS reads can be used for single molecule somatic mutation detection. We will take advantage of these PacBio CCS read properties to attempt single molecule meiotic recombination and gene conversion detection and define meiotic recombination and gene conversion rate. In addition, we will be able to use the single molecule somatic mutation detection method to screen for pathogenic de novo mutations. In the pilot phase, we will be sequencing sperm samples from three different individuals to determine the individual and age effect on meiotic recombination and gene conversion rate.

Type: Cancer Genomics
Archiver: European Genome-phenome Archive (EGA)

1 Dataset

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Dataset ID	Description	Technology	Samples
EGAD00001015736	Meiotic recombination is a fundamental process that generates genetic diversity by creating new combinations of existing alleles. While crossovers in humans are well characterized, the more frequent non-crossovers that lead to gene conversion remain challenging to study. Here we show that single high-fidelity long sequencing reads from sperm can capture both crossovers and non-crossovers, allowing effectively arbitrary sample sizes for analysis from one male. Using fifteen sperm samples from thirteen donors we demonstrate variation between donors for the different types of recombination, even when they share the same PRDM9 genotype. Non-crossovers are less consistent with the genetic map and exhibit reduced association with meiotic double-strand break (DSB) sites identified by DMC1 binding. Where non-crossover gene conversions are close to PRDM9 sites they tend to occur upstream. We further provide evidence for two distinct non-crossover processes. One gives rise to the vast majority of non-crossovers with mean conversion tract length under 50bp, while ~1% of non-crossovers have much longer mean tract length. Applying the same analysis pipeline to public data from twelve blood samples, we also see non-crossover gene conversions, but very few crossover events. These non-meiotic events, not correlated with the genetic map, increase with age, consistent with double-strand break repair throughout life. We suggest that many of the non-crossover events seen in sperm also derive from non-meiotic repair prior to spermatogenesis.	Revio Sequel IIe	1