Certain aneuploidies such as trisomy-21 (Downs syndrome), trisomy-18 (Edward syndrome), Turner syndrome (XO) etc are more common than others.
I had a vague thought that it is related to chromosome size: the chromosomes which are towards the extremes of size will be affected in an improper segregation event.
Chromosomes 13, 18, 21 and Y are among the smaller chromosomes in humans, and are commonly associated with aneuploidy (but 22 which is also small is not affected). The larger ones are unaffected (X is an anomaly).
I thought that longer ones should be more affected because more cohesin bridges have to be broken, but it seems that is not the case.
- Is there any association of chromosome size and frequency of aneuploidy?
- If the difference is because of differential lethalities then does the length correlation still hold true? Smaller the chromosomes, lesser the genes and hence lesser would be the effect of extra copy on the cellular biochemical networks.