This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cytogenetic Disorders, Subject name: Pathology
Kary oty pe 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., 47XXY Klinefelter syndromeo Klinefelter syndrome is the most common chromosomal disorder associated with male hypogonadism and infertility.o It is defined classically by a 47, XXY karyotype with variants demonstrating additional X and Y chromosomes. (Other variants can have 48 XXX Y. rarely 49 XXXXY or mosaics can be there with some cells containing normal 46, XY and others 47, XXY).o Classically, it results from meiotic non-dysjunctionof sex chromosomes (40% during spermatogenesis and 60% during oogenesis). Mostly, non-dysjunctionoccur during lstmeiotic division.