A Human Blood-Group Gene Intermediate between M and N

Abstract

WHILE many blood-group antigens have, subsequently to their discovery, proved to be divisible into a number of sub-types, the M and N antigens have shown little tendency to be subdivided. Aberrant M and N antigens have from time to time been described and attributed to corresponding genes, sometimes characterized as M ₂ and N ₂, but both of these are extremely rare, with frequencies of the order of 1 in 1,000 in all populations hitherto tested. It was therefore with great surprise that we found examples of an abnormal M antigen and also of an abnormal N in a single English family. The results of our tests on members of this family are shown in Table 1. The sera used have each been tested with consistent results against very many—in some cases thousands—other red cell samples. The classification of the sera into positive and negative reactors with members of the C. family depends solely on tests on members of that family and on incomplete tests on one other unrelated person. All the tests have been carried out at least in duplicate, and in the case of Mrs. C. and K. C. tests have been done on separate blood samples at intervals of several months.