{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,25]],"date-time":"2026-07-25T20:00:44Z","timestamp":1785009644291,"version":"3.55.0"},"reference-count":17,"publisher":"Oxford University Press (OUP)","issue":"4","license":[{"start":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T00:00:00Z","timestamp":1781049600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,6,10]]},"abstract":"Abstract<\/jats:title>\n \n Introduction<\/jats:title>\n ABO discrepancies caused by weak A subgroups are uncommon but clinically important because they can lead to mistyping and inappropriate transfusion management.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n We present the cases of 2 patients at an academic medical center who were historically typed as group O but were found to harbor weak A subgroups upon detailed investigation.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n In case 1, the patient\u2019s red blood cells demonstrated weak reactivity with anti-A reagent on forward typing, with anti-A1 and anti-B identified on reverse typing. In case 2, the patient\u2019s red blood cells were nonreactive with anti-A reagent on forward typing but did agglutinate with anti-A,B reagent. Reverse typing showed weak reactivity against A1 and A2 cells, with strong reactivity against B cells, consistent with an anti-A antibody. In both cases, molecular genotyping performed at a reference laboratory returned results consistent with an Aw or Ael allele.<\/jats:p>\n <\/jats:sec>\n \n Discussion<\/jats:title>\n These cases illustrate the serologic spectrum of weak A phenotypes, highlight the variable sensitivity of ABO reagents in detecting minimal antigen expression, and underscore the possible utility of molecular characterization when serologic results are ambiguous.<\/jats:p>\n <\/jats:sec>","DOI":"10.1093\/labmed\/lmag043","type":"journal-article","created":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T11:55:21Z","timestamp":1783598121000},"source":"Crossref","is-referenced-by-count":0,"title":["ABO discrepancies revealing rare weak A subgroups: a 2-case series"],"prefix":"10.1093","volume":"57","author":[{"given":"Ande","family":"Marchini","sequence":"first","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, University of Wisconsin\u2013Madison , Madison, WI,","place":["United 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