Zoology - Principles of Inheritance and Variation Question with Solution | TestHub

Chromosomal disorder occurs when there is addition or deletion of chromosome in the individual. In case of trisomy of the 21st chromosome causes Down's syndrome. XXY condition is called Klinefelter's syndrome where individual has an extra copy of X chromosome. In such condition, the individual shows overall masculine development but has feminine characteristic as well like breast development (Gynaecomastia). The individual is sterile but does not have any mental retardation unlike in Down's syndrome.