[3] He received the 2022 Shaw Prize in Life science and Medicine, together with Paul A. Negulescu, for their work that uncovered the physiological defects in cystic fibrosis and developed effective medications.
[1][3] He completed his residency in Internal Medicine at the University of Iowa Hospitals and Clinics,[3] during which the attending physicians supervising him induced his interest in research.
[5] After his residency, Welsh spent 3 years at the University of California, San Francisco and then University of Texas Medical School at Houston as a research fellow, returning to the University of Iowa in 1981 and becoming an assistant professor in the Department of Internal Medicine, eventually promoted to Professor of Internal Medicine and Professor of Molecular Physiology and Biophysics.
[15] His study also showed F508del-mutated CFTR protein can function properly if it reached cell surface,[16] paving the way for cystic fibrosis therapies.
In recent years, Welsh has developed animal models of cystic fibrosis, most notably in pigs, allowing for the study of the disease in an in vivo setting.