title: Novel deletion mutation of HLA-B*40:02 gene in acquired aplastic anemia.
abstract: Despite prevalence of clonal evolution in patients with aplastic anemia (AA), somatic mutation of human leukocyte antigen (HLA) gene is rarely reported. Herein, we reported a case of acquired AA (aAA) harboring a new four-base-pair deletion mutation within exon 4 of HLA-B*40:02 leading to frameshift and premature stop codon. The HLA-B*40:02 mutant allele was detected in the patient's peripheral blood sample not in patient's buccal epithelial cells. The patient received allogenic hematopoietic stem cell transplantation (HSCT) from HLA-matched sibling donor. On day 30 after HSCT, the mutant HLA allele was not detected by high-resolution sequence-based HLA typing. Serial chimerism analyses showed mixed chimeric status indicative of coexisting donor and recipient hematopoietic cells. Our data could provide additional support in view of pathophysiology of aAA that somatic mutation of HLA-B*40:02 allele is one of the possible origin of clonal escape to evade immune attack in patient with aAA.
authors.affiliation: Department of Laboratory Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: T-D
authors.identifier: http://orcid.org/0000-0002-3873-3117
authors.initials: TD
authors.lastname: Jeong
authors.affiliation: Division of Hematology & Oncology, Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Y-C
authors.initials: YC
authors.lastname: Mun
authors.affiliation: Department of Laboratory Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: H-S
authors.initials: HS
authors.lastname: Chung
authors.affiliation: Department of Laboratory Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: D
authors.initials: D
authors.lastname: Seo
authors.affiliation: Research and Development Team, Biowithus Life Science Institute, Seoul, Korea.
authors.forename: J
authors.initials: J
authors.lastname: Im
authors.affiliation: Department of Laboratory Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: J
authors.initials: J
authors.lastname: Huh
keywords: HLA-B; aplastic anemia; cytotoxic T lymphocyte; mutation