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Which one of the following conditions in humans is correctly matched with its chromosomal abnormality/linkage?
A
Erythroblastosis foetalis - X-linked
B
Down syndrome - 44 autosomes + XO
C
Klinefelter's syndrome - 44 autosomes + XXY
D
Colour-blindness - Y-linked
Detailed Solution
Klinefelter's syndrome is caused by the presence of an additional X chromosome in a male, giving the karyotype 47, XXY, i.e. 44 autosomes + XXY.
Such a person has overall masculine development, but feminine features such as gynaecomastia (development of breasts) are also expressed, and the individual is sterile.
So Klinefelter's syndrome - 44 autosomes + XXY is the correct match.
Erythroblastosis foetalis is due to Rh incompatibility between an Rh negative mother and an Rh positive foetus; the Rh gene is autosomal, not X-linked.
Down syndrome is trisomy of chromosome 21 (45 autosomes + XX or XY). The condition 44 autosomes + XO is Turner's syndrome.
Colour-blindness is a recessive X-linked trait, not Y-linked.
Such a person has overall masculine development, but feminine features such as gynaecomastia (development of breasts) are also expressed, and the individual is sterile.
So Klinefelter's syndrome - 44 autosomes + XXY is the correct match.
Erythroblastosis foetalis is due to Rh incompatibility between an Rh negative mother and an Rh positive foetus; the Rh gene is autosomal, not X-linked.
Down syndrome is trisomy of chromosome 21 (45 autosomes + XX or XY). The condition 44 autosomes + XO is Turner's syndrome.
Colour-blindness is a recessive X-linked trait, not Y-linked.