Question

Which one of the following condition in humans is correctly matched with its chromosomal abnormality/linkage ?

(a) Klinefelter's syndrome- 44 autosomes + XXY 

(b) Colour blindness - Y-linked 

(c) Erythroblastosis foetalis- X-linked 

(d) Down syndrome-- 44 autosomes + XO

Answer 1

Correct option (a) Klinefelter's syndrome- 44 autosomes + XXY

Explanation

Klinefelter's syndrome is represented by 44 autosomes + XXY. When an abnormal egg with XX chromosome is fertilised by a sperm carrying Y-chromosome a zygote having XXY sex chromosomes is formed. The resulting young one is an abnormal sterile male.

The 44 autosome  + XO condition is due to Turner,s syndrome. Such females are sterile and have short stature, webbed neck, broad shield-shaped chest, etc.

Down's syndrome is due to the trisomy of 21st pair of chromosome. It is characterised by moderate mental retardation, large tongue, short stature, stubby fingers, an enlarged liver and spleen. 

Colour blindness is an X-linked disease. The person suffering from this disease can't differentiate between red and green colours. 

Erythroblastosis foetalis is caused due to Rh factor in a child born due to marriage between Rh⁺ man and Rh^- woman.