{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T07:01:08Z","timestamp":1775804468700,"version":"3.50.1"},"reference-count":19,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T00:00:00Z","timestamp":1775779200000},"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>\n                    Transcobalamin II (\n                    <jats:italic>TCN2<\/jats:italic>\n                    ) deficiency is a rare autosomal recessive metabolic disorder that impairs vitamin B12 transport and can present with megaloblastic anemia and neutropenia, often mimicking hematologic diseases such as myelodysplastic syndrome (MDS). We report a 5-year-old male presenting with pallor, fatigue, and fever. On admission, he had acute anemia crisis and neutropenia, with chest CT revealing a lung infection, while serum folate and vitamin B12 levels were normal. Bone marrow smears and flow cytometry suggested possible MDS; however, genetic testing identified compound heterozygous pathogenic variants in the\n                    <jats:italic>TCN2<\/jats:italic>\n                    gene, confirming\n                    <jats:italic>TCN2<\/jats:italic>\n                    deficiency. Following parenteral methylcobalamin therapy, his symptoms improved and blood counts gradually normalized. Oral maintenance therapy was then initiated, with stable hematologic parameters during follow-up. This case highlights the importance of considering rare metabolic disorders such as\n                    <jats:italic>TCN2<\/jats:italic>\n                    deficiency in pediatric patients with unexplained anemia and neutropenia, and underscores the value of early recognition, genetic diagnosis, and long-term management. These findings contribute to the limited literature on pediatric\n                    <jats:italic>TCN2<\/jats:italic>\n                    deficiency and reinforce clinician awareness when evaluating children with MDS-like presentations.\n                  <\/jats:p>","DOI":"10.3389\/fped.2026.1757303","type":"journal-article","created":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T06:05:53Z","timestamp":1775801153000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Transcobalamin II deficiency mimicking myelodysplastic syndrome in a child: a case report"],"prefix":"10.3389","volume":"14","author":[{"given":"Xiangrong","family":"Hu","sequence":"first","affiliation":[{"name":"The First Hospital of Putian City","place":["Putian, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Huiping","family":"Xu","sequence":"additional","affiliation":[{"name":"The First Hospital of Putian City","place":["Putian, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Linjun","family":"Xie","sequence":"additional","affiliation":[{"name":"The First Hospital of Putian City","place":["Putian, China"]},{"name":"The School of Clinical Medicine, Fujian Medical University","place":["Fuzhou, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,4,10]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"1163","DOI":"10.1056\/NEJM197111182852103","article-title":"Neonatal megaloblastic Anemia due to inherited transcobalamin II deficiency in two siblings","volume":"285","author":"Hakami","year":"1971","journal-title":"N Engl J Med"},{"key":"B2","doi-asserted-by":"publisher","first-page":"461","DOI":"10.1007\/s10545-013-9664-5","article-title":"Update on transcobalamin deficiency: clinical presentation, treatment and 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