title: Autoimmunity Including Intestinal Behçet Disease Bearing the KRAS Mutation in Lymphocytes: A Case Report.
abstract: We experienced the case of a 3-year-old male with a very rare combination of autoimmunity, including immune thrombocytopenia, recurrent Henoch-Schönlein purpura and intestinal Behçet disease. Exome sequencing of the patient's peripheral blood mononuclear cells identified a KRAS G13C mutation. Interestingly, the KRAS G13C mutation was observed in T and B lymphocytes, as well as natural killer cells, but not granulocytes. Our case was completely phenotypically different from RASopathies and did not meet the criteria for Ras-associated lymphoproliferative disease or juvenile myelomonocytic leukemia. This is the first reported case in which the KRAS mutation existed only in the lymphoid lineage. Based on the findings of our case and the current literature, it is clear that the RAS mutation in lymphoid cells is tightly linked with various autoimmune symptoms. The presence of the RAS mutation in lymphocytes should be reconsidered as a pathogenesis in cases of autoimmunity.
authors.affiliation: Division of Pediatrics, hiroshi_moritake@med.miyazaki-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Moritake
authors.affiliation: Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan; and.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Takagi
authors.affiliation: Division of Pediatrics.
authors.forename: Mariko
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Department of Technology Development, Kazusa DNA Research Institute, Kisarazu, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ohara
authors.affiliation: Departments of Gastroenterology and Hematology, and.
authors.forename: Shojiro
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Pathology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan;
authors.forename: Sayaka
authors.initials: S
authors.lastname: Moriguchi
authors.affiliation: Division of Pediatrics.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nunoi
mesh_terms: D015551:Autoimmunity; D001528:Behcet Syndrome / Q000235:genetics / Q000276:immunology / Q000473:pathology; D002675:Child, Preschool; D004247:DNA / Q000235:genetics*; D004252:DNA Mutational Analysis; D059472:Exome; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009154:Mutation; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000378:metabolism
chemical_list: C117307:KRAS protein, human; D004247:DNA; D016283:Proto-Oncogene Proteins p21(ras)