What is considered the rarest phenotype of the Kidd blood type?

The rarest phenotype of the Kidd blood type is Jk(a-b-). This phenotype occurs when a person lacks both the Jk(a) and Jk(b) antigens on the red blood cells. The prevalence of this phenotype in various populations is significantly low compared to the more common Kidd phenotypes, such as Jk(a+b+) and Jk(a+b-) that have one or both of the antigens present. The rarity of Jk(a-b-) is clinically significant in transfusion medicine because individuals with this phenotype may have a higher risk of developing anti-Jk3 antibodies if they are transfused with blood from donors who express these antigens. This can complicate future transfusions as finding compatible blood becomes increasingly challenging. In contrast, the other phenotypes mentioned possess at least one of the antigens, making them more common in the general population.