The peculiar properties of pericentromeric regions of genomes and their influence on sex chromosome evolution.

Pericentromeric regions can promote low recombination near sex-determining loci, making extensive sex-linked regions likely a pre-existing feature linked to the centromere-effect.

• Why it matters: The work addresses whether recombination suppression must be actively invoked to explain sex-linked regions, or whether centromere-associated recombination patterns already account for them.
• What they did: It reviews genome-region properties that recombine rarely, focusing on pericentromeric regions and sex-linked regions overlapping them, and discusses gene-loss asymmetry and expression/gene-content differences.
• The result: It concludes that special signatures of recombination suppression are hard to distinguish, while Y- or W-linked major gene loss versus X- or Z-linked counterparts is common, and similar Y–X degeneration may occur when pericentromeric regions have ephemeral gene content and low expression.