A NOVEL VARIANT OF THE HUMAN BLOOD-GROUP K1 ANTIGEN

A discrepancy in duplicate anti-K1 typing in a parentage case led to t he discovery of an unusual K1 blood group antigen. Red blood cells fro m the propositus (JC) express a rare variant of the K1 antigen that is detectable by only 8 of 72 sera containing anti-K1. Absorption and el ution studies using reactive anti-K1 confirmed the presence of a K1 an tigen. Nonreactive anti-K1 was not absorbed by or eluted from JC's red blood cells, Red cells from 3 of the propositus's siblings also had t he variant K1 antigen. The variant antigen exhibited qualitative as we ll as quantitative differences as compared to normal K1, and we have n amed it K1var.