Trisomy 8 usually leads to early miscarriage of a fetus. However, adult individuals have been found with cells that have three copies of chromosome 8 in them. How can this be?
A) The trisomic 8 adults likely have a mosaic region with trisomy 8.
B) The trisomic cells underwent complete nondisjunction.
C) The trisomic cells underwent a meiotic nondisjunction.
D) This individual must be triploid.

Question

Quizplus · Accepted Answer

Trisomy 8 usually results in early miscarriage. However, in rare instances, an individual may survive with cells that contain three copies of chromosome 8. This is most commonly due to mosaicism, where the individual has a mix of cells with a normal number of chromosomes and cells with an extra chromosome 8. This can happen when a chromosome replicates improperly during cell division, resulting in an extra copy of chromosome 8 in some cells. Mosaicism can occur during embryonic development, allowing some cells to survive with an extra chromosome while others do not.

Trisomy 8 Usually Leads to Early Miscarriage of a Fetus