This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Karyotype of klienfelter syndrome is? 
Select and explain. 
A. 47XXY, B. 45XO, C. 46XXY, D. 45XXX
A: 47XXY
Answer: A: 47XXY 
Explanation: Ans. is 'a' i.e., 47XXYKlinefelter syndromeKlinefelter syndrome is the most common chromosomal disorder associated with male hypogonadism and infeility.It is defined classically by a 47, XXY karyotype with variants demonstrating additional X and Y chromosomes.(Other variants can have 48 XXXY, rarely 49 XXXXY or mosaics can be there with some cells containing normal 46,XY and others 47, XXY).Classically, it results from meiotic non-dysjunctionof sex chromosomes (40% during spermatogenesis and 60% during oogenesis). Mostly, non-dysjunctionoccur during lstmeiotic division.