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After 25 years as co-editor of Immunogenetics, Masanori Kasahara has stepped down. Ronald Bontrop and I will miss him enormously. His intelligence, humility, understated humor, and, most of all, his competence combine to define Masanori as a scientist’s scientist, or as we say in the USA “one in a million.”

Masanori earned his MD in 1980 and his PhD in 1984 at the University of Hokkaido, where he examined the serology of MHC class II molecules. He did his postdoc at the Max Planck Institute for Biology in Tubingen with Jan Klein, examining the genetics of mouse chromosome 17 and the MHC of non-human primates, where he and others studied trans-species evolution of MHC alleles. Masanori’s independent work first involved a testes-specific gene encoded on mouse chromosome 17, tpx1, and later tpx2. He moved to the University of Miami in 1986, where Jan Klein had set up a second lab in the United States. Masanori ran this lab during the “off season” in Miami, and began his rise to an independent position there.

On a personal level, Masanori and I have collaborated since our early days at the University of Miami, when I moved there from the Basel Institute for Immunology in 1987. When he became an independent investigator, Masanori expanded his research from non-human primate MHC to general evolution of the immune system. With patience far exceeding that of Job, Masanori succeeded in mentoring me in molecular biology techniques, and together we cloned many of the first MHC genes in amphibians and sharks. We have continued to collaborate to this day on basic-science projects and on several review articles (which have been a lot of fun to write together).

Unfortunately for me, and for the University of Miami, Masanori returned to Hokkaido in 1992 as an Associate Professor, rapidly rising through the ranks over the next 28 years to become Professor, Dean, and finally Acting President of the university. His crowning scientific achievement was attained in 1996, when he discovered four MHC paralogous regions in the mouse and human genomes, consistent with a proposed two rounds of genome duplication proposed by Ohno in 1970. This discovery of the MHC paralogous regions was nearly simultaneous with work done in another lab uncovering four paralogous regions of hox genes in jawed vertebrates and only one such region in the invertebrates. Since those discoveries, as expected, one can find paralogous regions for any syntenic group of genes found in the Gnathostomes. Currently, we are close to uncovering the origins of the MHC (and other adaptive immune genes) through comparative genomic analyses. This progress was made possible by Masanori’s groundbreaking work in 1996, which provided the framework for understanding the evolution of large genetic regions.

Masanori has also done pioneering work on the thymic-specific proteasome β5t, nonclassical class I molecules recognized by NKG2D, and on the Agnathan Variable Lymphocyte Receptors. His papers are written in an incomparable, lucid style with nary a word out of place. One day I saw on his desk a review of one of his papers, which said, “I don’t think I’ve ever read another paper written with such precision.” High praise indeed, but not a surprising accolade to those who have known and worked with Masanori. His dedication to Immunogenetics, which was founded by his mentor Jan Klein, will never be forgotten.