This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
Kilnefelter no of chromosomes 
Select and explain. 
A. 47, B. 46, C. 45, D. 44
A: 47
Answer: A: 47 
Explanation: Klinefelter syndrome is best defined as male hypogonadism that develops when there are at least two X chromosomes and one or more Y chromosomes. Most affected patients have a 47,XXY karyotype. This karyotype results from nondisjunction of sex chromosomes during meiosis. The extra X chromosome may be of either maternal or paternal origin. (Robbins Basic Pathology, 9 th edition. page : 239)