Question

How many of the following disorders can be classified as chromosomal disorders?
Sickle-cell anaemia, Turner’s syndrome, Cri-du-chat syndrome, Edwards syndrome

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is C 3

Genetic disorders that are caused due to addition or deletion or abnormal arrangement of one or more chromosomes are called chromosomal disorders.

Cri-du-chat syndrome, Turner’s syndrome and Edwards syndrome are types of chromosomal disorders in human beings.

The partial deletion of the $5^{th}$ chromosome results in Cri-du-chat syndrome.

Trisomy refers to the presence of three copies of a particular chromosome instead of two. It is represented as 2n+1 in humans, where 2n refers to the normal diploid set.

Trisomy of the ${18}^{th}$ chromosome results in Edwards syndrome.

Monosomy refers to the lack of one chromosome from the normal set of 46 chromosomes in humans, represented as 2n-1. Monosomy of the X chromosome in females results in Turner's syndrome. Affected females are sterile.

On the contrary, sickle-cell anaemia is a type of Mendelian disorder which is caused due to mutation in a single gene.