Dr. Gregersen has been a leader in defining the genetics of rheumatoid arthritis and other autoimmune diseases. He was among the first to clone and sequence the major MHC class II alleles associated with rheumatoid arthritis and he formulated the “shared epitope” hypothesis to explain these complex associations in the mid 1980’s. This work has remained seminal in the field, and he has continued to collaborate on refinements of this hypothesis. In the 1990’s he founded and led the North American Rheumatoid Arthritis Consortium (NARAC) which carried out the first major Genome Wide Associations Studies (GWAS) in this disease; this has become an international consortium that continues to expand genetic understanding of rheumatoid arthritis. There are now over 100 confirmed regions of genetic associations with RA, including PTPN22, the first major genetic associations outside of the MHC which was identified in 2004 by the NARAC team. He subsequently formed and co-directed the Multiple Autoimmune Diseases Genetics Consortium (MADGC) which continues to drive genetic work into many other common autoimmune disorders.
He has extended this work into understanding the functional significance of these associations, with a particular focus on relating risk alleles for quantitative immune traits that may form targets for improved diagnosis and therapy. To facilitate these investigations, he established a nationally available “living biobank” of over 7,500 subjects (www.gapregistry.org) who are genotyped for the autoimmune disease risk loci and can be recalled for investigational studies on the basis of genotype.
His other research interests include the genetic and environmental contributions to neurocognitive phenotypes: absolute pitch, synesthesia, and autistic spectrum disorder (ASD). He has documented the prevalence of absolute pitch, its dependence on both genetic and environmental factors, and its relationship to synesthesia, with which it overlaps genetically. Recent collaborative work has provided evidence that the intrauterine immune environment contributes to the risk for austistic spectrum disorders. Most recently, Dr. Gregersen has turned his attention to the study of endometriosis, an understudied condition that affects the lives of 5% of US women and is associated with pain, disability and infertility.
In 2007 Dr. Gregersen was the recipient of the Klemperer Medal from New York Academy of Medicine as well as the Distinguished Basic Investigator Award from the American College of Rheumatology. He was elected to membership in the Association of American Physicians in 2009. He was awarded the Crafoord Prize from the Royal Swedish Academy of Sciences in 2013.