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

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

Author information

1
Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
2
Department of Laboratory Testing, Japanese Red Cross Tohoku Block Blood Center, Miyagi, Japan.
3
Department of Cell Science, Institute of Biomedical Sciences, Fukushima Medical University, Fukushima, Japan.
4
Department of Research and Development, Japanese Red Cross Central Blood Institute, Tokyo, Japan.
5
Department of Blood Transfusion and Transplantation Immunology, Fukushima Medical University Hospital, Fukushima, Japan.
6
Blood Group Section, Japanese Red Cross Kanto-Koshinetsu Block Blood Center, Tokyo, Japan.

Abstract

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.

PMID:
31020675
DOI:
10.1111/trf.15319

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