Jean-Laurent Casanova received his M.D. in 1987 and his Ph.D. in 1992, after training at the Pasteur Institute in Paris and the Ludwig Institute for Cancer Research in Lausanne. He was appointed professor at Necker in 1999 and with Laurent Abel, cofounded the Laboratory of Human Genetics of Infectious Diseases. He was appointed professor at Rockefeller University in 2008 and named HHMI investigator in 2014. He continues to partner with Dr. Abel, maintaining their lab in Paris and NY. Casanova studies the human genetic and immunological determinants of life-threatening infectious diseases. He searches for rare and common single-gene mutations that selectively compromise immunity of otherwise healthy individuals who are vulnerable to specific infectious diseases. He then searches for other causes disrupting the same mechanisms of host defense, and thus characterizes the causal mechanisms of life-threatening infectious diseases.