Patricia A. Jacobs (1934–2026)

Patricia Ann Jacobs died on the March 15, 2026, aged 91 years. In her late 80s, she developed Alzheimer disease, and her final three years were spent in a nursing home until she died shortly after suffering a major stroke. Pat will be principally remembered as a founder of the science of human cytogenetics when in 1959, Jacobs and Strong showed that males with Klinefelter Syndrome had a chromosome constitution of 47, XXY. This observation also confirmed that the Y chromosome was male-determining in humans.