<prompt> Kilnefelter no of chromosomes47464544  <response>: 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 