Question

Barr body is absent in somatic cell of
1. Klinefelter syndrome individual
2. Tripple X syndrome individual
3. Turner syndrome individual
4. Sub-human mammalian female individual

Answer 1

Correct Answer - Option 3 : Turner syndrome individual

The correct answer is Turner syndrome individual.

• There is no Barr body in Turner because they only have one X.
• Turner individuals are just X (typically denoted “XO” to show the absence of the second sex chromosome).
• In Turner syndrome, a woman lacks part or all of one of her X chromosomes (leaving her with just one functional X).
• People with this disorder develop as females, but often have short stature and may exhibit symptoms like infertility and learning difficulties.

• The Barr body, also sometimes called the sex chromatin, is the inactive X chromosome in female somatic cells.
  • In all of the female somatic cells, which don’t take part in sexual reproduction, one of the X chromosomes is active, and the other is inactivated in a process called lyonization, becoming the Barr body.
• Klinefelter syndrome (KS) happens in men who have more than one X chromosome (XXY).
  • Males have a single X chromosome from their mother and a single Y one from their father. Males with KS get at least one extra X from either parent.
• Triple X syndrome, in which a woman has an XXX genotype.
  • Women with an XXX genotype have female sex characteristics and are fertile (able to have children).
  • In some cases, triple X syndrome may be associated with learning difficulties, late development of motor skills in infants, and problems with muscle tone.