Question

Why do we abbreviate trisomy as n + 1?

Answer 1

Here's the reason.

Explanation:

Firstly I would like to throw some light that `n+1` is not an abbreviation of trisomy.

General abbreviation of trisomy is `2n+1`.

`n` is the haploid number of chromosomes at a certain sequence.

Now, it's diploid is `2n`.

Now, haploidy & diploidy are common intermediates of chromosomes.

But, an abnormal count of chromosomes is called aneuploidy.

Some aneuploid conditions are `rarr`

(1). `2n − 1` `rarr` monosomy.
(because only one copy of same specific chromosome is present).

(2). `n+1` `rarr` disomy.
(because two copies of same specific chromosome is present).

(3). `2n + 1` `rarr`trisomy.
(because three copies of same specific chromosome is present).

(4). `2n − 2` `rarr`nullisomy.
(because no copy of a specific chromosome is present).

Hope it Helps:).