With trisomy of the X chromosome, the karyotype of a woman is manifested – 47, XXX. What are the reasons for the appearance

With trisomy of the X chromosome, the karyotype of a woman is manifested – 47, XXX. What are the reasons for the appearance of such a chromosome set in humans?

1) a woman with a violation of meiosis occurs nondisjunction of chromosomes;
2) abnormal eggs are formed, containing two X chromosomes instead of one;
3) during fertilization, a gamete with an abnormal set of chromosomes (22 autosomes + XX) merges with a normal spermatozoon (22 autosomes + X), as a result, a zygote with such a set of chromosomes is formed: 22 pairs of autosomes + XXX.

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