Curt Jacob Stern studied radiation and chromosomes in humans and fruit flies in the United States during the twentieth century. He researched the mechanisms of inheritance and of mitosis, or the process in which the chromosomes in the nucleus of a single cell, called the parent cell, split into identical sets and yield two cells, called daughter cells. Stern worked on the Drosophila melanogaster fruit fly, and he provided early evidence that chromosomes exchange genetic material during cellular reproduction. During World War II, he provided evidence for the harmful effects of radiation on developing organisms. That research showed that mutations can cause problems in developing fetuses and can lead to cancer. He helped explain how genetic material transmits from parent to progeny, and how it functions in developing organisms.

In 1938, physician Henry Hubert Turner published “A Syndrome of Infantilism, Congenital Webbed Neck, and Cubitus Valgus,” hereafter “A Syndrome of Infantilism,” in the journal Endocrinology, in which he described a condition that researchers later named Turner syndrome. Turner syndrome is a genetic condition that affects biological females, characterized by a partially or completely missing X chromosome. In the paper, Turner describes a previously unrecognized set of symptoms in seven different females, including a lack of physical and sexual development, infertility, webbed neck, and elbow deformities, among others. Turner also records various methods of hormone treatments for his patients, such as growth hormone and estrogen injections. “A Syndrome of Infantilism” was one of the first published descriptions of Turner syndrome, a developmental condition that affects one in 2,500 live female births globally, and highlighted the use of hormone treatments to promote the development of stunted physical and sexual growth.