Shortly after the development of the antiglobulin test for the detection of red cell
antibodies, the first example of a Kidd antibody was reported in 1951. A patient, Mrs.
Kidd, was described who produced an antibody that caused hemolytic disease in her newborn
son. After determining that the new antigen was independent of the other then-known blood
groups, it was given the name Jka. Soon afterwards, the allele
was found by Plaut and designated Jkb. In 1959, the first
example of the null phenotype, i.e., Jk(a-b-), was founnd in a woman who had produced an
antibody that appeared to be anti-Jka plus anti-Jkb.
Since the specificities were inseparable, the antibody was renamed anti-Jk3 which
recognizes an antigen found whenever Jka or Jkb
is present. To date, no low frequency antigens have been associated with the Kidd blood
The first example of the Jk(a-b-) phenotype was found in a woman who experienced
a delayed transfusion reaction. She was a Filipino of some Chinese and Spanish ancestry.
Another family of Filipino-Chinese ancestry was reported that contained three Jk(a-b-)
members. Since these first reports, many such individuals of Asian or Polynesian
extraction have been identified. One study found a total of 66 (0.9%) Jk(a-b-) donors
among 7425 tested; all were of Polynesian backgrounds. Other populations reporting this
phenotype include tribes from Mato Grasso, Brasil, Hindus from India and Japanese blood
donors. The Jk(a-b-) phenotype is strikingly absent from Caucasians although rare cases
have been found in a French, an Australian and a Finnish family. The molecular basis for
Jknull has been shown to be splice-site and misense mutations,
as well as a partial gene deletion. The Jka/Jkb
polymorphism is a A8386 base pair change at amino acid 280, changing Asp to Asn.
Interestingly, the Jk(a-b-) red cells were shown to be resistant to lysis in high
concentrations of urea as opposed to normal cells that completely lyze in ~1 minute. This
observation led to biochemical studies which identified the Kidd antigens on the urea
transport protein which is found not only in red blood cells but also in the kidney. One
study of individuals with the Jk(a-b-) phenotype has reported that they have a decreased
ability to concentrate urine but this does not appear to cause a health problem.