HD Glossary

Note: Some words can have differing definitions depending on the context in which they are used. The definitions presented here are the ones that best apply to the words as they are used. HDSA is grateful to the Stanford Hopes website for their contribution and maintenance of this glossary.



  • Y chromosome - One of the two sex chromosomes (the other is the X chromosome). Males have one X and one Y. Females have two X’s.