Principles of Inheritance and Variation Question 208
208. In human beings, 45 chromosomes/single $X /$ XO abnormality causes
[1992]
(a) Down’s syndrome
(b) Kinefelter’s syndrome
(c) Turner’s syndrome
(d) Edward’s syndrome
Show Answer
Answer : c
Hints & Solution
(c) Turner’s syndrome encompassess several chromosomal abnormalities, of which monosomy $X$ is the most common. It occurs in 1 out of every 2500 female births. Instead of the normal XX sex chromosomes for a female, only one $X$ chromosome is present and fully functional. This is called $45, X$ or $45, X 0$, although other genetic variants occur. In Turner’s syndrome, female sexual characteristics are present but generally underdeveloped.
