Answers are grounded in this paper and cite their sources.
Four Kp(a-b-) Japanese sisters, the product of a consanguineous mating, have otherwise normal Kell antigens. Kpc, a 'new' allele of Kpa and Kpb is the most probable background.
No takes yet. Share an insight, caveat, or question.
Yamaguchi et al. (1979) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: