Two novel KEL alleles encoding K0 phenotypes in Brazilians

K0 (null) is a rare phenotype in which no Kell antigens are expressed on the red blood cell (RBC) membrane. Anti-Ku seen in K0 individuals has previously been shown to cause hemolytic disease of newborn and severe hemolytic transfusion reactions. Several molecular mechanisms associated with the K0 phenotype have already been described, including those that lead to alternative RNA splicing, premature stop codons, and amino acid changes that affect protein trafficking. We herein report two novel KEL alleles encoding K0 phenotypes in Brazilians. We analyzed genomic DNA of two unrelated Caucasian females referred to our reference laboratory. Both patients were phenotyped as K−, k−, Kp(a−), Kp(b−), Js(a−), Js(b−) and presented an antibody reactive 2+ in gel indirect antiglobulin test with all RBCs except their own.