Integrative genome analysis identified the KANNO blood group antigen as prion protein

Transfusion. 2019 Jul;59(7):2429-2435. doi: 10.1111/trf.15319. Epub 2019 Apr 24.


Background: Anti-KANNO, a broadly reactive RBC alloantibody, is found among some Japanese pregnant women, but the genetic basis of the corresponding antigen remains unclear.

Study design and methods: We integrated a statistical approach to identify the coding gene for KANNO antigen by conducting a genome-wide association study (GWAS) on four KANNO-negative individuals and 415 healthy Japanese. We also applied whole-exome sequencing to them and performed a replication study to confirm the identified genome variation using independent 14 KANNO-negative individuals. A monoclonal antibody-specific immobilization of erythrocyte antigens (MAIEA) assay was used to locate KANNO antigen on RBC-specific membrane protein. In vivo and in vitro binding assays of anti-KANNO were further applied to the cells expressing a candidate protein.

Results: The GWAS revealed a genome-wide significant association of chromosome 20p13 locus (p = 2.76E-08; odds ratio > 1000 [95% confidence interval = 48-23,674]). The identified single-nucleotide polymorphism located in an intronic region of the prion protein (PRNP) gene. Whole-exome sequencing revealed a missense variant in the PRNP gene (rs1800014, E219K), which is in linkage disequilibrium with the single-nucleotide polymorphism identified in the GWAS. All 18 KANNO-negative individuals possessed the homozygous genotype of the missense variant. The MAIEA assay using anti-KANNO and mouse antihuman prion protein showed a clear difference between KANNO-positive and KANNO-negative RBCs. Anti-KANNO showed direct binding to CHO-K1 cells expressing wild-type PRNP but not to those expressing E219K PRNP.

Conclusion: We first identified the coding gene of the high-frequency antigen KANNO located in PRNP and the missense variation (E219K) that affects the seropositivity of the KANNO antigen, which were confirmed by PRNP overexpressed cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Group Antigens / genetics*
  • Chromosomes, Human, Pair 20 / genetics*
  • Gene Frequency*
  • Genome, Human*
  • Genome-Wide Association Study
  • Glycoproteins / genetics*
  • Humans
  • Polymorphism, Single Nucleotide*
  • Prion Proteins / genetics*


  • Blood Group Antigens
  • Glycoproteins
  • KANNO antigen, human
  • PRNP protein, human
  • Prion Proteins