M.C ESCHER'S "BOND OF UNION" © 2015 THE M.C ESCHER COMPANY — THE NETHERLANDS. ALL RIGHTS RESERVED. WWW.MCESCHER.COM
In 1976, researchers from the Lister Institute of Preventive Medicine in London published the puzzling case of a woman who had two different blood types: 93 percent of her red cells were type O, while the remaining 7 percent were type A1, the most common type A subgroup.1 A few years later, Winifred Watkins of the MRC Clinical Research Centre and colleagues came across another blood donor with two distinct red blood cell types, and further investigation led to an even more astonishing finding: a phenotypically normal man, with presumably XY cells in his testes and most of his body, was found to carry XX cells in his skin and other tissues.2
These case studies heralded a new appreciation for the phenomenon of genetic chimerism—when ...
