Long-read whole-genome sequencing-based concurrent haplotyping and aneuploidy profiling of single cells

Abstract

Long-read whole-genome sequencing (lrWGS) enhances haplotyping by providing more phasing information per read compared to short-read sequencing. However, its use for single-cell haplotype phasing remains underexplored. This proof-of-concept study examines lrWGS data from single cells for small variant (single nucleotide variant (SNV) and indel) and structural variation (SV) calling, as well as haplotyping, using the Genome in a Bottle (GIAB) Ashkenazi trio. lrWGS was performed on single-cell (1 cell) and multi-cell (10 cells) samples from the offspring. Chromosome-length haplotypes were obtained by leveraging both long reads and pedigree information. These haplotypes were further refined by replacing them with matched parental haplotypes. In single-cell and multi-cell samples, 92% and 98% of heterozygous SNVs, and 74% and 78% of heterozygous indels were accurately haplotyped. Applied to human embryos for preimplantation genetic testing (PGT), lrWGS demonstrated 100% consistency with array-based methods for detecting monogenic disorders, without requiring phasing references. Aneuploidies were accurately detected, with insights into the mechanistic origins of chromosomal abnormalities inferred from the parental unique allele fractions (UAFs). We show that lrWGS-based concurrent haplotyping and aneuploidy profiling of single cells provides an alternative to current PGT methods, with applications potential in areas such as cell-based prenatal diagnosis and animal and plant breeding.