Down syndrome (Trisomy 21) and Klinefelter's syndrome (XXY) are both a result of an extra chromosome due to which type of mutation?

Question

Responses

Frameshift
Frameshift

Deletion
Deletion

Nondisjunction
Nondisjunction

Insertion

Answer 1

Both Down syndrome (Trisomy 21) and Klinefelter's syndrome (XXY) are results of an extra chromosome due to nondisjunction. Nondisjunction refers to the failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to gametes with an abnormal number of chromosomes. If such a gamete contributes to fertilization, the resulting zygote will have an extra chromosome.