Peer-reviewed article
Case Report: Imerslund Grasbeck syndrome: a rare cause of megaloblastic anemia in a well-nourished child.
Khurana R, Kanvinde P, Mudaliar S ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This is a medical case report describing diagnosis and treatment of a rare genetic disorder (Imerslund-Gräsbeck syndrome) in a single 7-year-old child. The report documents clinical presentation, diagnostic findings, and initiation of vitamin B12 therapy. It is a specialized clinical case study rather than a study of child well-being outcomes or interventions.
Key points
- A 7-year-old boy with severe macrocytic anemia was found to have a homozygous AMN gene mutation causing Imerslund-Gräsbeck syndrome despite adequate dietary intake
- Initial presentation included rash, fatigue, oral ulceration, pallor, and growth parameters between 10th-25th centiles
- Investigations showed hemoglobin of 2.5 g/dL, markedly reduced vitamin B12 levels, and leukopenia
- Genetic testing confirmed diagnosis after ruling out other causes of B12 deficiency
- Treatment involved parenteral vitamin B12 therapy with plans for lifelong supplementation
Limitations
This is a single case report with no comparison group or outcome data, so it cannot provide evidence about intervention effectiveness or generalized outcomes. The report focuses on diagnosis and initial management rather than long-term child well-being impacts.
Abstract
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-Gräsbeck syndrome (IGS), a rare autosomal recessive condition characterized by selective intestinal malabsorption of vitamin B12 due to mutations in the CUBN or AMN 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 g/dL), leukopenia, thrombocytopenia, markedly reduced vitamin B12 levels (<50 pg./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 AMN 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.