A chromosomal disorder caused due to loss of one X chromosome in huma…

The correct answer is Option (3) → Turner’s syndrome

A chromosomal disorder is caused by the absence, excess or wrong arrangement of one or more chromosomes.

Option (1) Down’s syndrome — Incorrect. Down’s syndrome is caused by an extra copy of chromosome 21 (trisomy 21), not by the loss of an X chromosome.

Option (2) Klinefelter’s syndrome — Incorrect. It is caused by an extra X chromosome in a male (47, XXY). It is the opposite case: one X too many.

Option (3) Turner’s syndrome — Correct. Turner’s syndrome is caused by the absence of one X chromosome: 45 with X0 (44 + XO). Such females are sterile, as the ovaries are rudimentary, and lack other secondary sexual characters.

Option (4) Acquired immuno deficiency syndrome — Incorrect. AIDS is caused by a virus (HIV), not by a chromosomal change. “Acquired” means it is not inherited.

Note: A similar question was also asked in CUET (UG) 2026 on 25-05-2026 (Slot 1).

NCERT Extract:
Chromosomal Disorders – “… Turner’s Syndrome : Such a disorder is caused due to the absence of one of the X chromosomes, i.e., 45 with X0, Such females are sterile as ovaries are rudimentary besides other features including lack of other secondary sexual characters (Figure 4.17 b).”

Figure 4.17 Diagrammatic representation of genetic disorders due to sex chromosome composition in humans : (a) Klinefelter Syndrome; (b) Turner’s Syndrome