The karyotype of an individual was found to be 44 + XXY. The individu…

The correct answer is Option (3) → Klinefelter's Syndrome

Option (1) Haemophilia — Incorrect. Haemophilia is a Mendelian disorder: a sex-linked recessive defect in a protein needed for blood clotting. It comes from a change in a single gene; the chromosome number stays normal (44 + XY or 44 + XX).

Option (2) Down's Syndrome — Incorrect. Down’s syndrome is caused by an extra copy of chromosome 21 (trisomy 21), an autosome. The sex chromosomes stay normal, so the karyotype is 45 + XX or 45 + XY, not 44 + XXY.

Option (3) Klinefelter's Syndrome — Correct. In Klinefelter’s syndrome the person has one extra X chromosome, so the sex chromosomes are XXY in place of XY. With the 44 autosomes this gives 44 + XXY, which NCERT writes as 47, XXY (47 chromosomes in all). Such a person develops as a male, but some female features also appear, such as development of the breasts (gynaecomastia), and the person is sterile.

Option (4) Turner's Syndrome — Incorrect. Turner’s syndrome is caused by the absence of one X chromosome in a female, so the karyotype is 44 + XO (45, X0), not 44 + XXY.

NCERT Extract:
Chromosomal Disorders – “… Klinefelter’s Syndrome : This genetic disorder is also caused due to the presence of an additional copy of X-chromosome resulting into a karyotype of 47, XXY. Such an individual has overall masculine development, however, the feminine development (development of breast, i.e., Gynaecomastia) is also expressed (Figure 4.17 a).”

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