A combination of the effects of rare genotypes at the XK and KEL blood
group loci results in absence of Kell system antigens from the red blood
cells
GL Daniels, F Weinauer, C Stone, M Ho, CA Green, H Jahn-Jochem, R Offner and AP Monaco
Bristol Institute for Transfusion Sciences, UK.
The 22 antigens of the Kell blood group system are located on a red blood
cell (RBC) membrane glycoprotein that shows sequence homology with a family
of metalloendopeptidases. Expression of the Kell system antigens is
partially governed by XK, an X-linked gene that encodes the Kx protein;
absence of Kx results in reduced Kell antigen expression. Almost total
absence of Kell antigens from the RBCs of a German man with no symptoms of
neuroacanthocytosis could not be due to the Kell- null phenotype, Ko,
because his RBCs had very weak expression of Kx antigen and his three
children were Kp(a + b+). Kell antigens were normal on the RBCs of his son
but weak on those of his two daughters. An Nla III restriction
fragment-length polymorphism within the KEL gene showed the Kpa/Kpa
genotype in the propositus. Sequencing of his XK gene showed a single base
change within the donor splice consensus sequence of intron 2. A BsaAl
restriction fragment-length polymorphism showed the mutation in both of his
daughters but not in his son. The extreme depression of the Kell antigens
of the propositus must be due to a combination of effects, ie, homozygosity
for Kpa and deficiency of Kx protein, each of which is capable of causing
some degree of weakening of Kell antigens.
Volume 88,
Issue 10,
pp. 4045-4050,
11/15/1996
Copyright © 1996 by The American Society of Hematology
