A vasectomy is a surgery that works to inhibit reproduction by interrupting the passage of sperm through the vas deferens, a tube in the male reproductive system. The procedure is a method of inhibiting an individual’s ability to cause pregnancy through sexual intercourse without altering the other functions of the penis and testes. In the US, into the early 1900s, proponents of eugenics, the belief that human populations can be made better by selecting for so-called desirable traits, used the procedure to forcibly sterilize people whom they deemed undesirable. Despite its early associations with eugenics, physicians’ use of vasectomy eventually transitioned into an option for elective contraception. Even with the various shifts in motivation for performing vasectomies, as of 2023, patients have the choice to undergo a sterilization procedure if they want to restrict their own ability to have children.

X-linked severe combined immunodeficiency, or X-SCID, is a chromosomal disorder in which the immune system lacks multiple protective cells that defend the body from disease. As of 2024, approximately one in 75,000 males have X-SCID. X-SCID is the most common type of SCID, which encompasses a range of disorders that all involve defects in immune cells that fight infections, leaving the individual susceptible to life-threatening diseases. X-SCID, which typically only affects males, arises due to a mutation in the interleukin 2 receptor gamma chain, or IL-2RG, gene on the X chromosome. IL-2RG aids certain immune cells to develop their protective functions, so a mutation in the receptor results in a dysfunctional immune system. Doctors most commonly use bone marrow transplants to treat X-SCID. By studying cases of X-SCID, researchers more clearly defined the role of lymphocytes in immune system development and overall disease protection. Unless detected and treated early, the defect in immune cells from X-SCID makes the individual prone to severe, recurrent infections, which are almost always fatal.