Question

Number of Barr body present in a female child with down syndrome.

• A. $0$
• B. $1$
• C. $2$
• D. All are correct

Answer 1

The correct option is A $0$

In humans with more than one X chromosome, the number of Barr bodies visible at interphase is always one fewer than the total number of X chromosomes. For example, men with Klinefelter syndrome (47,XXY karyotype) have a single Barr body, whereas women with a 47,XXX karyotype have two Barr bodies. A female human with down syndrome, no barr bodies appear.

So, the correct option is ‘0’.