Although recombination is essential to the successful completion of human meiosis, it remains unclear how tightly the process is regulated and over what scale. To assess the nature and stringency of constraints on human recombination, we examined crossover patterns in transmissions to viable, non-trisomic offspring, using dense genotyping data collected in a large set of pedigrees. Our analysis supports a requirement for one chiasma per chromosome rather than per arm to ensure proper disjunction, with additional chiasmata occurring in proportion to physical length. The requirement is not absolute, however, as chromosome 21 seems to be frequently transmitted properly in the absence of a chiasma in females, a finding that raises the possibility of a back-up mechanism aiding in its correct segregation. We also found a set of double crossovers in surprisingly close proximity, as expected from a second pathway that is not subject to crossover interference. These findings point to multiple mechanisms that shape the distribution of crossovers, influencing proper disjunction in humans.

Original publication

DOI

10.1371/journal.pgen.1000658

Type

Journal article

Journal

PLoS genetics

Publication Date

18/09/2009

Volume

5

Addresses

Department of Human Genetics, University of Chicago, Chicago, Illinois, United States of America.

Keywords

Chromosomes, Human, Pair 21, Humans, Chromosome Segregation, Recombination, Genetic, Crossing Over, Genetic, Female, Male