Individuals with Klinefelter syndrome have an XXY set of sex chromosomes. Which
ID: 152336 • Letter: I
Question
Individuals with Klinefelter syndrome have an XXY set of sex chromosomes. Which of these describes a way this abnormality can arise? Select all that apply Nondisjunction during meiosis I in the mother results in an XX egg which is fertilized by a Y sperm from the father. Nondisjunction during meiosis II in the mother results in an XX egg, which is fertilized by a Y sperm from the father. Nondisjunction during meiosis I in the father results in an XY sperm which fertilizes an X egg. Nondisjunction during meiosis II in the father results in an XY sperm, which fertilizes an X egg.Explanation / Answer
Klinefelter syndrome is not inherited, these chromosomal changes occur usually as random events during the formation of reproductive cells (eggs and sperms) in a parent. An error in cell division called nondisjunction results in a representative cell with an abnormal number of chromosomes.
With respect to female parent (mother) meiosis II is the stage which leads to cells with an extra X chromosome.
And in males the condition occurs in meiosis I only
So options 2nd and 3rd in the above question are correct.