This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetic and genetic disorders, Subject name: Pediatrics
Barr body is absent in female having _______ 
Select and explain. 
A. 46 XX genome, B. 45 XO Genome, C. 47 XXX, D. All of the above
B: 45 XO Genome
Answer: B: 45 XO Genome 
Explanation: Barr body is absent in female having 45 XO genome. Barr body: Densely staining inactivated condensed X chromosome present in each somatic cell of a female is found in the nucleus. Chromatid body (Barr body or sex chromatin) is derived from one of the two X Chromosomes which became inactivated The number of Barr bodies is thus one less than the number of X chromosomes. Turner&;s syndrome is female without Barr body. Klinefelter&;s syndrome is male with Barr body. Ref: Concepts of genetics 11th edition Pgno: 208