What is aneuploidy and its types?

Aneuploidy:

1. The chromosomal abnormality is caused due to abnormal chromosome numbers in cells.
2. The abnormal chromosome number is due to the presence or absence of a chromosome.

Types of Aneuploidy:

1. Hyper Aneuploidy: The type of chromosomal abnormality is caused due to presence of one, or two extra copies of chromosomes.

• Trisomy:

1. The type of hyper aneuploidy is characterized by an extra copy of a chromosome in cells.
2. The chromosomal composition is represented by (2N+1).
3. Down syndrome and Klinefelter syndrome are examples of trisomy.

• Tetrasomy:

1. The type of hyper aneuploidy is characterized by an extra copy of a pair of chromosomes in cells.
2. The chromosomal composition is represented by (2N+2).
3. Tetrasomy 12p (Pallister-Killian syndrome) is an example of tetrasomy.

2. Hypo Aneuploidy: The type of chromosomal abnormality is caused due to absence or loss of one or two chromosomes.

• Monosomy:

1. The type of hyper aneuploidy is characterized by the loss of one chromosome in cells.
2. The chromosomal composition is represented by (2N-1).
3. Turner's syndrome is an example of monosomy.

• Nullisomy:

1. The type of hyper aneuploidy is characterized by the loss of a pair of chromosomes in cells.
2. The chromosomal composition is represented by (2N-2).