A patient, mosaic for Rh and Fy antigens lacking other signs of chimerism or chromosomal disorder.

A patient who shows two populations of RBC, differing in their Rh and Fy antigens, was investigated but no other sign of chimerism or mosaicism in a variety of other antigenic systems, including serum and enzyme polymorphisms and HLA antigens, was observed. His karyotype, as investigated on lymphocyte and fibroblast cultures, was normal. Possible explanations of the observed phenomenon are discussed.