2. Based on the image given below, select the option that describes it correctly:

(1) Q-banded normal human karyotype.
(2) G-banded human karyotype depicting aneuploidy.
(3) C-banded karyotype depicting Klinefelter syndrome.
(4) G-banded normal human karyotype.

Reading the karyotype

• Autosomes 1–22 appear as pairs, so autosome number is normal (no extra or missing autosomes).

• Sex chromosomes are labeled XXY: two X chromosomes and one Y chromosome.

• This corresponds to 47, XXY, the classical karyotype of Klinefelter syndrome.

The banding pattern shown is centromere‑focused, consistent with C‑banding, which strongly stains constitutive heterochromatin near centromeres, giving solid dark blocks rather than the fine longitudinal G‑ or Q‑bands.

Option-wise explanation

1. Q-banded normal human karyotype

   • Q-banding uses quinacrine fluorescence and shows bright/dim bands along chromosome arms, and a normal karyotype would have XX (female) or XY (male).

   • The image instead shows centromeric C‑bands and an XXY complement, so this is incorrect.

2. G-banded human karyotype depicting aneuploidy

   • Aneuploidy is present (XXY), but the banding is not G‑banding; G‑bands show longitudinal dark/light patterns after trypsin–Giemsa, which are not seen here.

   • Thus this description only partly fits.

3. C-banded karyotype depicting Klinefelter syndrome – correct

   • C‑banding matches the bold centromeric staining pattern.

   • XXY sex chromosomes diagnose Klinefelter syndrome, so this option accurately describes both the banding method and the chromosomal abnormality.

4. G-banded normal human karyotype

   • Wrong on both counts: the karyotype is not normal (XXY) and the banding is C‑, not G‑banding.

Therefore the best description of the given image is C-banded karyotype depicting Klinefelter syndrome (option 3).