Jean-Laurent Casanova is a Professor at The Rockefeller University, Howard Hughes Medical Institute Investigator, and Head of the St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch. He is also a Professor at the Necker Hospital for Sick Children, Paris Descartes University, where the Necker Branch of the Laboratory is located. Jean-Laurent received his PhD from the Pierre et Marie Curie Paris University in 1992 and received his MD in 1995. In 1999 he was appointed a Professor of Pediatrics at Necker, where, with Laurent Abel, he cofounded and co-directed the Laboratory of Human Genetics of Infectious Diseases. He was recruited by The Rockefeller University in 2008. Work in his laboratory tests the hypothesis that severe infectious diseases may result from single-gene inborn errors of immunity. He has discovered genetic etiologies of various infectious diseases, including viral, bacterial, and fungal diseases.