{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,4]],"date-time":"2026-03-04T10:46:09Z","timestamp":1772621169228,"version":"3.50.1"},"reference-count":10,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,3,4]],"date-time":"2026-03-04T00:00:00Z","timestamp":1772582400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Human leukocyte antigen (HLA) matching is critical for donor selection in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Each HLA locus is normally biallelic; however, exceptionally rare cases with more than two alleles at a single locus have been reported.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case presentation<\/jats:title>\n                    <jats:p>We describe a 17-year-old male with mixed phenotype acute leukemia (T\/myeloid) who was found to carry three alleles at both the HLA-B and HLA-C loci during pre-transplant evaluation. Family-based HLA typing revealed that the additional alleles were inherited as part of a single maternal haplotype shared by multiple siblings. Flow cytometric analysis using antisera with known HLA specificity demonstrated that all three HLA-B and HLA-C alleles were expressed on the cell surface. Because this unusual immunogenetic configuration precluded the identification of an unrelated donor, a sibling donor sharing the same triple-allele haplotype was selected despite a single HLA-A mismatch. Allo-HSCT was successfully performed, with manageable graft-versus-host disease.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>This case highlights an extremely rare immunogenetic configuration in which triple-allele expression at two HLA class I loci directly influenced donor selection for allo-HSCT. Comprehensive interpretation of HLA typing results, including family analysis and protein-level expression, is essential when such atypical findings are encountered.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fimmu.2026.1785227","type":"journal-article","created":{"date-parts":[[2026,3,4]],"date-time":"2026-03-04T05:42:15Z","timestamp":1772602935000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Allogeneic hematopoietic stem cell transplantation in a patient with triple-allele expression at both HLA-B and HLA-C loci"],"prefix":"10.3389","volume":"17","author":[{"given":"Yoshiyuki","family":"Fujita","sequence":"first","affiliation":[{"name":"Department of Hematology, Hyogo Medical University","place":["Nishinomiya, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kyoko","family":"Yoshihara","sequence":"additional","affiliation":[{"name":"Department of Hematology, Hyogo Medical University","place":["Nishinomiya, Japan"]},{"name":"Department of Transfusion Medicine and Cellular Therapy, Hyogo Medical University Hospital","place":["Nishinomiya, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daisuke","family":"Takahashi","sequence":"additional","affiliation":[{"name":"Japanese Red Cross Society Blood Service Headquarters Central Blood Research Institute","place":["Tokyo, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hidenori","family":"Tanaka","sequence":"additional","affiliation":[{"name":"HLA Foundation Laboratory","place":["Kyoto, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yusuke","family":"Kino","sequence":"additional","affiliation":[{"name":"HLA Foundation Laboratory","place":["Kyoto, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fuyuki","family":"Yamagata","sequence":"additional","affiliation":[{"name":"Department of Hematology, Hyogo Medical University","place":["Nishinomiya, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mami","family":"Samori","sequence":"additional","affiliation":[{"name":"Department of Hematology, Hyogo Medical University","place":["Nishinomiya, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Saki","family":"Takahashi","sequence":"additional","affiliation":[{"name":"Department of Hematology, Hyogo Medical University","place":["Nishinomiya, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Satoshi","family":"Yoshihara","sequence":"additional","affiliation":[{"name":"Department of Hematology, Hyogo Medical University","place":["Nishinomiya, Japan"]},{"name":"Department of Transfusion Medicine and Cellular Therapy, Hyogo Medical University Hospital","place":["Nishinomiya, 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