{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T04:30:36Z","timestamp":1786595436631,"version":"build-2736575974"},"reference-count":6,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T00:00:00Z","timestamp":1786579200000},"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. Nutr."],"abstract":"<jats:p>\n                    Megaloblastic anemia, characterized by macrocytic anemia, is most commonly caused by nutritional vitamin B12 deficiency; however, inherited disorders of cobalamin absorption should be considered in children with adequate dietary intake. One such disorder is Imerslund\u2013Gr\u00e4sbeck syndrome (IGS), a rare autosomal recessive condition characterized by selective intestinal malabsorption of vitamin B12 due to mutations in the\n                    <jats:italic>CUBN<\/jats:italic>\n                    or\n                    <jats:italic>AMN<\/jats:italic>\n                    genes. We report a 7-year-old boy, born of a third-degree consanguineous marriage, who presented with generalized rash, easy fatigability, and recurrent oral ulceration. Examination revealed pallor and hyperpigmented knuckles without organomegaly. Growth parameters were between the 10th and 25th centiles. Investigations showed severe macrocytic anemia (hemoglobin 2.5\u202fg\/dL), leukopenia, thrombocytopenia, markedly reduced vitamin B12 levels (&amp;lt;50\u202fpg.\/mL), and peripheral smear findings of macrocytosis with hypersegmented neutrophils. In view of adequate nutritional intake, further evaluation for malabsorption was undertaken. There was no clinical evidence of gastrointestinal malabsorption, and anti-intrinsic factor antibody testing was negative. Urinalysis demonstrated mild proteinuria. Genetic analysis identified a homozygous mutation in the\n                    <jats:italic>AMN<\/jats:italic>\n                    gene, confirming the diagnosis of IGS. The child started on parenteral vitamin B12 therapy with plans for lifelong supplementation at intervals guided by clinical response. IGS should be suspected in children with megaloblastic anemia despite adequate dietary intake, particularly in the presence of proteinuria, parental consanguinity, or a poor response to oral supplementation. Early diagnosis and timely initiation of lifelong vitamin B12 therapy are essential to ensure optimal hematological recovery, growth, and neurodevelopmental outcomes.\n                  <\/jats:p>","DOI":"10.3389\/fnut.2026.1883519","type":"journal-article","created":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T04:23:44Z","timestamp":1786595024000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Imerslund Grasbeck syndrome: a rare cause of megaloblastic anemia in a well-nourished child"],"prefix":"10.3389","volume":"13","author":[{"given":"Ritika","family":"Khurana","sequence":"first","affiliation":[{"name":"Department of Paediatric Hematology-Oncology, Bai Jerbai Wadia Hospital for Children","place":["Mumbai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Purva","family":"Kanvinde","sequence":"additional","affiliation":[{"name":"Department of Paediatric Hematology-Oncology, Bai Jerbai Wadia Hospital for Children","place":["Mumbai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sangeeta","family":"Mudaliar","sequence":"additional","affiliation":[{"name":"Department of Paediatric Hematology-Oncology, Bai Jerbai Wadia Hospital for Children","place":["Mumbai, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,8,13]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"208","DOI":"10.1111\/j.1651-2227.1960.tb07724.x","article-title":"Idiopathic chronic megaloblastic anemia in children","volume":"49","author":"Imerslund","year":"1960","journal-title":"Acta Paediatr"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"289","DOI":"10.1111\/j.0954-6820.1960.tb03549.x","article-title":"Selective vitamin B12 malabsorption and proteinuria in young people","volume":"167","author":"Grasbeck","year":"1960","journal-title":"A syndrome Acta Med Scand"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1186\/1750-1172-1-17","article-title":"Imerslund-Gr\u00e4sbeck syndrome (selective vitamin B12 malabsorption with proteinuria)","volume":"1","author":"Gr\u00e4sbeck","year":"2006","journal-title":"Orphanet J Rare Dis"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"291","DOI":"10.1186\/s13023-023-02889-x","article-title":"Imerslund-Gr\u00e4sbeck syndrome: a comprehensive review of reported cases","volume":"18","author":"Kingma","year":"2023","journal-title":"Orphanet J Rare Dis"},{"key":"ref5","doi-asserted-by":"publisher","first-page":"25","DOI":"10.1007\/s44162-026-00168-4","article-title":"Treatment strategies for Imerslund-Gr\u00e4sbeck syndrome: a systematic review of vitamin B12 dosage and routes of administration","volume":"5","author":"Hassan","year":"2026","journal-title":"J Rare Dis"},{"key":"ref6","doi-asserted-by":"publisher","first-page":"103880","DOI":"10.1016\/j.ejmg.2020.103880","article-title":"Imerslund-Gr\u00e4sbeck syndrome presenting with microangiopathic hemolytic anemia in a child","volume":"63","author":"Gurlek Gokcebay","year":"2020","journal-title":"Eur J Med Genet"}],"container-title":["Frontiers in Nutrition"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fnut.2026.1883519\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T04:23:45Z","timestamp":1786595025000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fnut.2026.1883519\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,13]]},"references-count":6,"alternative-id":["10.3389\/fnut.2026.1883519"],"URL":"https:\/\/doi.org\/10.3389\/fnut.2026.1883519","relation":{},"ISSN":["2296-861X"],"issn-type":[{"value":"2296-861X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,13]]},"article-number":"1883519"}}