XO-chromosomal abnormally in human beings causes

Options

A. Turner's syndrome
B. Down's syndrome
C. Klinefelter's syndrome
D. none of these

Answer

A

Explanation

Turner's syndrome is characterised by the monosomy of XO type. It is characterised by a lack of ovaries and menstrual cycle. Affected women are sterile and lack secondary sexual characteristics , although the external genitalia are persent. The syndrome is named after the US endocrinologist H.H. Turner (1892-1970), who first described it.
Down's syndrome is a congenital form of mental retardation due to a chromosome defect in which there are three copies of chromosome no. 21 instead of the usual two . The affected individual has a short board face and slanted eyes (as in the Mongalian races), short fingers, and weak muscles. Down's syndrome can be detected before birth by amniocentesis. It is named after the British physician John Down (1828-96), who first syndrome is characterised by trisomy (XXY). These are male individuals, who are phenotypically fairly normal but have a fairly low sperm count and therefore sterile.