{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T06:20:37Z","timestamp":1783405237964,"version":"3.54.6"},"reference-count":13,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T00:00:00Z","timestamp":1783382400000},"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. Pediatr."],"abstract":"<jats:p>Herein, we describe a 22-month-old girl who presented with isolated severe thrombocytopenia (nadir platelet count: 6\u2009\u00d7\u200910\u2079\/L) without overt microangiopathic hemolysis. The patient exhibited a partial clinical response to both corticosteroids and intravenous immunoglobulin (IVIG). Bone marrow examination showed increased megakaryocytes, with platelet-producing megakaryocytes accounting for 15% of the total megakaryocyte population. Initial whole-exome sequencing (WES) yielded negative findings for definitive pathogenic variants and clinically significant copy number variations (CNVs). Subsequent targeted genetic testing identified compound heterozygous ADAMTS13 variants: a paternally derived heterozygous exon 8 deletion validated by quantitative PCR (qPCR), and a maternally derived heterozygous frameshift mutation c.2764_2767dup (p.Ala923ValfsTer66) in exon 22 confirmed by Sanger sequencing. Functional analysis revealed severely diminished ADAMTS13 activity (0.23%) with undetectable inhibitory antibodies. The patient\u2019s family history was remarkable for a first-trimester miscarriage and a previous neonatal death attributed to severe thrombocytopenia complicated by pulmonary hemorrhage. This case highlights two critical diagnostic pitfalls of pediatric hTTP: atypical presentation with isolated thrombocytopenia and misleading partial responsiveness to immunosuppressive therapy. In addition, routine WES has inherent limitations in detecting exon-level CNVs and certain frameshift variants. For children with unexplained recurrent thrombocytopenia and a suggestive familial bleeding history, ADAMTS13 functional assessment and targeted genetic sequencing should be performed promptly, even if initial WES results are unremarkable.<\/jats:p>","DOI":"10.3389\/fped.2026.1875502","type":"journal-article","created":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T05:45:47Z","timestamp":1783403147000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Hereditary thrombotic thrombocytopenic purpura mimicking immune thrombocytopenia: diagnostic pitfalls of whole-exome sequencing"],"prefix":"10.3389","volume":"14","author":[{"given":"Nannan","family":"Xie","sequence":"first","affiliation":[{"name":"Cangzhou People\u2019s Hospital","place":["Cangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yan","family":"He","sequence":"additional","affiliation":[{"name":"Cangzhou People\u2019s Hospital","place":["Cangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Danlei","family":"Wu","sequence":"additional","affiliation":[{"name":"Cangzhou People\u2019s Hospital","place":["Cangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,7]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"392","DOI":"10.1056\/NEJMc1915670","article-title":"Hereditary thrombotic thrombocytopenic Purpura","volume":"382","author":"Hamroun","year":"2020","journal-title":"N Engl J Med"},{"key":"B2","doi-asserted-by":"publisher","first-page":"2836","DOI":"10.1182\/blood-2016-10-709857","article-title":"Thrombotic thrombocytopenic purpura","volume":"129","author":"Joly","year":"2017","journal-title":"Blood"},{"key":"B3","doi-asserted-by":"publisher","first-page":"1228","DOI":"10.3390\/diagnostics13071228","article-title":"Pitfalls of thrombotic microangiopathies in children: two case reports and literature review","volume":"13","author":"Mocanu","year":"2023","journal-title":". 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