Polymorphic variation in human meiotic recombination

Abstract

In this study, our phenotype of interest is meiotic recombination. Using genotypes of approximately 6,000 SNP markers in members of the Centre d'Etude du Polymorphisme Humain Utah pedigrees, we found extensive individual variation in the number of female and male recombination events. The locations and frequencies of these recombination events vary along the genome. In both female and male meiosis, the regions with the most recombination events are found at the ends of the chromosomes. Our analysis also shows that there are polymorphic differences among individuals in the activity of the recombination "jungles"; these preferred sites of meiotic recombination differ greatly among individuals. These findings have important implications for understanding genetic disorders that result from improper chromosome segregation.

Figure 1.

Identification of recombination events. For the genotype of each child, we determined the grandparental origin. Then, we scanned along the paternal and maternal chromosomes separately and assigned a recombination event when there was a switch from one grandparental origin to the next. GF = grandfather; GM = grandmother.

Figure 2.

Individual variation in the number of recombination events per meiosis. The graphs show the number of recombination events per meiosis in each individual. The panels show data for men (top) and women (bottom). The number of recombination events per meiosis is shown as a dot. Individuals are arranged in ascending order of the average number of recombination events per meiosis.

Figure 3.

Variation in recombination events across the human genome. The graphs show the number of recombination events per 5-Mb bin on each chromosome. The number of recombination events in each 5-Mb bin is plotted separately for men (blue) and for women (red). The five bins with the largest number of recombination events are indicated by blue and red dots for men and women, respectively.

Figure 4.

Polymorphic activity in recombination jungles. For three female and three male recombination jungles, the proportions of recombination events observed in each subject are shown. The expected number of recombination events is given to indicate deviation of the observed events from the expected. In each jungle, the individuals who recombined more frequently than expected (P<.05) are shown with an asterisk (*). The black columns represent data for the mother of family 1331 and the father of family 1340. Data for all subjects (34 women and 33 men) are shown, including those who did not recombine in the jungles (0 in the right sides of the graphs).