Question

How is aneuploidy important in humans?

Answer 1

Definition of aneuploidy :

1. Having missing or extra chromosomes is a condition called aneuploidy.
2. The risk of having a child with an aneuploidy increases as woman ages.
3. Trisomy is the most common aneuploidy. In trisomy, there is an extra chromosome. A common trisomy is Down syndrome (trisomy 21). Other trisomy include Patau syndrome (trisomy 13) and Edwards syndrome (trisomy 18). Monosomy is another type of aneuploidy in which there is a missing chromosome. Common monosomy is Turner syndrome, in which a female has a missing or damaged X chromosome.

Importance of aneuploidy :

1. Aneuploidy is common in humans, occurring in an average of 20–40%. It is the most common cause of miscarriages and congenital defects.
2. Most aneuploidy results from maternal meiotic. However, there is a remarkable variation of the chromosomes the way in which errors originate, where there are multiple mechanisms by which human aneuploidy occurs.
3. Studies of human fetal oocytes indicate a high level of recombination errors.
4. Cell cycle control checkpoints that operate in the meiotic prophase and at the metaphase–anaphase transition are less stringent in females than in males. Consequently, abnormal cells that are eliminated in spermatogenesis may escape detection in the female, ultimately leading to aneuploid eggs.
5. Studies suggest that loss of proteins over the female's reproductive life contributes to the maternal age effect on human trisomy.
6. Exposure to endocrine disruptors (bisphenol A) disrupts oogenesis at multiple stages and predisposes the oocyte to aneuploidy.