<prompt> What is the karyotype that you expect in chromosomal studies in a young male with hypogonadism and infeility and suspected Klinefelter syndrome?47XXY45X046XXY45XXX  <response>: Klinefelter syndrome is the most common chromosomal disorder associated with male hypogonadism and infeility. It is defined classically by a 47XXY karyotype with variants that demonstrate additional X and Y chromosomes. The syndrome is characterized by hypogonadism small testes, azoospermia, oligospermia, gynecomastia in late pubey, psychosocial problems, hyalinization and fibrosis of the seminiferous tubules, and elevated urinary gonadotropin levels. 