Question

The trisomy for ${21^{st}}$ chromosome is called as
(A) Down’s syndrome
(B) Turner’s syndrome
(C) Sickle cell anemia
(D) Klinefelter’s syndrome

Answer 1

Hint: Trisomy 21 is defined as the genetic disorder that occurs in the children due to the presence of one extra chromosome in the pair of 21 chromosomes. Thus, on the whole 47 chromosomes are present in the trisomy 21 diseased individual.

Complete Answer:
Trisomy21: This disease is caused by the presence of 47 chromosomes due to the one extra chromosome that is three copies of chromosome 21 instead of two pairs.

Symptoms: It includes delaying of physical growth, slanting eyes in the flat head, hypertelorism, mongoloid face, protruding tongue, folded skin in the eyelids, irregularly shaped ears, very small head, ligaments are loose in nature, short neck and the white pigments in the iris of the human eye. It is also known as Down syndrome, autosomal trisomy and autosomal aneuploidy.

Turner’s syndrome is the disorder in the female in which one of the X chromosomes is missing or partly missing. Sickle cell anemia is an inherited disorder in which the red blood cells are not healthy to carry oxygen. The Klinefelter syndrome is the disorder that the male has the one extra X chromosome in him.

Thus, the option (A) is correct.

Note: This disease occurs in the child of 8 - 10 years old. This is mainly caused by the unusual or irregular cell division that occurs in the male or female gametes at the time of development of sperm or egg cell. This affects the brain and the body development of the baby that is developed from that irregular gametes.