A Rare Example of Weakened Expression of the Kell (K1) Antigen

Abstract

Random typing of donor units revealed a donor whose red blood cells gave very weak reactions with all anti-Kell (anti-K1) antisera. All other Kell-system antigens (including Kx) and antigens of other red-cell systems tested were normal. This weak K1 antigen was present in four generations of the donor’s family. The red-cell morphology is normal in all family members with the weakened K1 antigen. A consistent hypothesis is that the weak antigen is inherited through a variant allele at the Kell locus and represents a quantitative, not a qualitative, change.

A KEL gene encoding serine at position 193 of the Kell glycoprotein results in expression of KEL1 antigen

“…KEL1, the original Kell antigen, is no exception. There is one report of an apparent qualitative KEL1 variant in a KEL:1 individual with a KEL1‐like antibody 11 and two other reports of weak or variant KEL1 that were not associated with anti‐KEL1 production 12,13 . None of these variants was investigated at the molecular level.…”

Molecular Basis of Kell Blood Group Phenotypes

“…In other rare cases, red cells have a diminished expres sion of one of the Kell antigens while the others have a nor mal expression [12,39], We have sequenced KEL DNA from one such individual. DNA from a person expressing weak KEL2 had a C1388T mutation in exon 11 leading to an alanine to valine change at residue 423 [unpubl.…”

A Novel Variant of the Human Blood Group K1 Antigen

“…An\ Bgabc, Bpa, Bxa, By\ Crawford, Dha, Fra, Hga, Hov/Wu, Ina, JFV, Lsa, Moa, Or, Osa, Pta, RASM, Rba, Rda, Ska, Swa, Toa, Tra, Vga, Wb, Wda, WESa. AL's serum was also tested with RBCs from the donor described by Kline et al [3]. The reactivity with this donor's RBCs was significantly less than with JC's or K:l,2 RBCs.…”

“…Hawley et al [2] described a donor whose RBCs were not agglutinated by any anti-Kl but did absorb and elute some examples of anti-Kl, imply ing a quantitative and qualitative change in the Kl anti gen. Kline et al [3] reported a donor whose RBCs were agglutinated weakly by all anti-Kl sera tested. This weak Kl antigen was present on RBCs in 4 generations and represents a quantitative change.…”