Blood Group Chimerism as a Clue to Generalized Tissue Mosaicism

Blood group studies disclosed mosaicism of the red cells in a healthy male Negro donor who was subsequently also found to have mosaicism of skin and bone marrow with respect to XX-XY chromosomal constitution and whose skin showed unequal pigmentation. The two red cell populations were unequal in numbers with a ratio of approximately 10:1. The major population was group A, Jk^a negative and showed the sickling trait in wet films and by electrophoresis. The minor population was group B, Jk^a positive, did not sickle and contained only hemoglobin A. Both red cells were Le^a positive despite the fact that the propositus was a secretor. However, only A substance was secreted and it was demonstrated by salivary studies and with the help of complete family studies, that the minor genetic product which had produced the group B erythrocytes represented the gene contribution se se and was the source of Le^a substance sufficient to coat both red cell populations. The family studies showed that the propositus had received a 2 allele contribution from each parent and was therefore the result of double fertilization of a double egg nucleus presumably an ovum and a polar body.