alleryStart learning →What is the relationship between Down syndrome and maternal age?
AIncidence rises with increasing maternal age
BIncidence falls with increasing maternal age
CIncidence is unrelated to the age of the mother
DIncidence peaks only in very young mothers
Answer & Solution
Correct answer: A. Incidence rises with increasing maternal age
1. Down syndrome arises when nondisjunction leaves a gamete with two copies of chromosome 21.
2. The risk of nondisjunction increases with the age of the parents.
3. The incidence of Down syndrome is therefore correlated with maternal age.
4. Older women are more likely to become pregnant with fetuses carrying the trisomy 21 genotype.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 13 "Modern Understandings of Inheritance", section 13.2 Chromosomal Basis of Inherited Disorders_
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