Genome-wide variation in recombination in female meiosis: a risk factor for non-disjunction of chromosome 21.
Altered recombination patterns along non-disjoined chromosomes is the first molecular correlate identified for non-disjunction in humans. To understand better the factors related to this correlate, we have asked to what extent is recombination altered in an egg with a disomic chromosome: are patterns limited to the non-disjoined chromosome or do they extend to the entire cell? More specifically, we asked whether there is reduced recombination in the total genome of an egg with a non-disjoined chromosome 21 and no detectable recombination. We chose this subclass of non-disjoined chromosomes to enrich potentially for extremes in recombination. We found a statistically significant cell-wide reduction in the mean recombination rate in these eggs with non-disjoined chromosomes 21; no specific chromosomes were driving this effect. Most importantly, we found that this reduction was consistent with normal variation in recombination observed among eggs. Thus, given that recombination is a multifactorial trait, these data suggest that when the number of genome-wide recombination events is less than some threshold, specific chromosomes may be at an increased risk for non-disjunction. Further studies are required to confirm these results, to determine the importance of genetic and environmental factors that regulate recombination and to determine their impact on non-disjunction.
Brown
A S
AS
Department of Genetics, Emory University School of Medicine, 1462 Clifton Road North-East, Atlanta, GA 30322, USA, asavage@genetics.emory.edu
Feingold
E
E
Broman
K W
KW
Sherman
S L
SL
D000328:Adult; D016022:Case-Control Studies; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D005260:Female; D005819:Genetic Markers; D015894:Genome, Human; D006801:Humans; D006822:Hybrid Cells; D008540:Meiosis / Q000235:genetics*; D011995:Recombination, Genetic; D012307:Risk Factors; D014314:Trisomy / Q000235:genetics*
D005819:Genetic Markers