AGAP duplicons associate with structural diversity at Chromosome 10q11.22

Area of Science:

• Genomics
• Human Genetics
• Evolutionary Biology

Background:

• The 10q11.22 chromosomal region is a complex, duplication-rich area of the human genome.
• This locus contains genes linked to intellectual disability, bipolar disorder, and obesity, highlighting its clinical significance.

Purpose of the Study:

• To characterize the structural diversity and understand the mechanisms driving genomic instability at the 10q11.22 locus.
• To investigate the role of segmental duplications (SDs) in shaping this genomic region.

Main Methods:

• Analysis of 64 haploid genome assemblies from the Human Pangenome Reference Consortium.
• Identification and characterization of alternative haplotypes and their structural variations.
• Breakpoint analysis to determine the mechanisms of recombination and rearrangement.

Main Results:

• Discovery of 11 alternative haplotypes with significant variations in copy number and orientation of large genomic segments (hundreds of kbp to >1 Mbp).
• Identification of a 2.4 Mbp size difference between the shortest and longest haplotypes.
• Genomic instability is driven by nonallelic homologous recombination between SD pairs, with recombination hotspots at high sequence identity (>99.6%).
• Recurrent inversions within SDs create new predispositions to copy-number variations.

Conclusions:

• The 10q11.22 locus exhibits substantial structural diversity and genomic instability, primarily mediated by SDs.
• SD architecture is linked to the AGAP gene family, suggesting a role in evolution over the last 25 million years.
• Findings expand the understanding of SD-mediated rearrangements and their impact on human genome variation.