Association between Maternal Age and Meiotic Recombination for Trisomy 21

• Published in: American journal of human genetics Vol. 76; no. 1; pp. 91 - 99
• Main Authors: Lamb, Neil E., Yu, Kai, Shaffer, John, Feingold, Eleanor, Sherman, Stephanie L.
• Format: Journal Article
• Language: English
• Published: Chicago, IL Elsevier Inc 01.01.2005; University of Chicago Press; Cell Press; The American Society of Human Genetics
• Subjects: Adult; Age; Biological and medical sciences; Cell division; Chromosome aberrations; Chromosome Mapping; Chromosomes; Chromosomes, Human, Pair 21; Down Syndrome - genetics; Female; General aspects. Genetic counseling; Genetic Markers; Genetic recombination; Humans; Maternal Age; Medical genetics; Medical sciences; Meiosis; Mothers; Nondisjunction, Genetic; Pregnancy; Recombination, Genetic; Risk Factors; Chromosomal aberration; Human; Trisomy 21; Recombination; Trisomy; Maternal age; Association; Chromosome G21; Aneuploidy; Genetics; Meiosis
• ISSN: 0002-9297; 1537-6605
• DOI: 10.1086/427266

Altered genetic recombination has been identified as the first molecular correlate of chromosome nondisjunction in both humans and model organisms. Little evidence has emerged to link maternal age—long recognized as the primary risk factor for nondisjunction—with altered recombination, although some studies have provided hints of such a relationship. To determine whether an association does exist, chromosome 21 recombination patterns were examined in 400 trisomy 21 cases of maternal meiosis I origin, grouped by maternal age. These recombination patterns were used to predict the chromosome 21 exchange patterns established during meiosis I. There was no statistically significant association between age and overall rate of exchange. The placement of meiotic exchange, however, differed significantly among the age groups. Susceptible patterns (pericentromeric and telomeric exchanges) accounted for 34% of all exchanges among the youngest class of women but only 10% of those among the oldest class. The pattern of exchanges among the oldest age group mimicked the pattern observed among normally disjoining chromosomes 21. These results suggest that the greatest risk factor for nondisjunction among younger women is the presence of a susceptible exchange pattern. We hypothesize that environmental and age-related insults accumulate in the ovary as a woman ages, leading to malsegregation of oocytes with stable exchange patterns. It is this risk, due to recombination-independent factors, that would be most influenced by increasing age, leading to the observed maternal age effect.