The Most Common Cause for Trisomy Events in Human Beings

Question

The most common cause for trisomy events in human beings is:
A) Normal disjunction during meiosis
B) Non-disjunction during meiosis
C) Normal disjunction during oogenesis
D) Normal disjunction during spermatogenesis
E) None of these is a cause for trisomy

Accepted Answer

Non-disjunction during meiosis is the most common cause of trisomy events in humans. Non-disjunction occurs when homologous chromosomes fail to separate properly during meiosis, resulting in one gamete with an extra chromosome and another with a missing chromosome. When the affected gamete is fertilized, a zygote with three copies of a particular chromosome is formed, leading to trisomy.