00596nz a2200217n 4500 230628|||anznnbab||||||||||||||a|||||||d homoit0002885 https://homosaurus.org/v3/homoit0002885 homoit XXYY syndrome Intersex variations https://homosaurus.org/v3/homoit0000669 People with XXYY syndrome are born with an extra copy of both an X and Y chromosome, resulting in an 48XXYY chromosome pattern instead of the typical 46XY. People with XXYY chromosomes may have undescended testes and produce lower-than-typical amounts of testosterone, which can cause them to start puberty at a later age than typical and develop less pronounced secondary sex characteristics like muscle tone and facial hair. They may also experience breast growth. People with XXYY syndrome often have other physical features that are similar to those developed by people with Klinefelter syndrome (47XXY).