A "new" phenotype confirming a relationship between Cra and Tca.

The red cells of two sisters had very weak Cra and Tca antigens and reacted only weakly with the antibody of the Cr(a-) Tc(a-)person, Inab. Both sisters had an antibody, named anti-Dra, to a high frequency antigen absent from their own cells and Inab cells but present on Cr(a-) Tc(a+) and on Cr(a+) Tc(a-) cells. This is the third example in which both Cra and Tca antigens are either absent or show weakened expression on the red cells, but the first case in which the unusual phenotype is shown to be inherited.