Imerslund-Grasbeck syndrome
Findings
No curated finding names Imerslund-Grasbeck syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Imerslund-Grasbeck syndrome (IGS) or selective vitamin B12 (cobalamin) malabsorption with proteinuria is a rare autosomal recessive disorder characterized by vitamin B12 deficiency commonly resulting in megaloblastic anemia, which is responsive to parenteral vitamin B12 therapy and appears in childhood.
Definition from the Mondo Disease Ontology (MONDO:0009853), read 2026-09-29. CC BY 4.0.
Features
30 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Abnormal circulating 5-methyltetrahydrofolate concentrationHPOHP:0410216
- Obligate (100% of cases)
- Decreased circulating vitamin B12 concentrationHPOHP:0100502
- Obligate (100% of cases)
- Malabsorption of Vitamin B12HPOHP:0200118
- Obligate (100% of cases)
- Hypersegmentation of neutrophil nucleiHPOHP:0004821
- Very frequent (80% to 99% of cases)
- Macrocytic anemiaHPOHP:0001972
- Very frequent (80% to 99% of cases)
- Megaloblastic anemiaHPOHP:0001889
- Very frequent (80% to 99% of cases)
- Abnormal hemoglobin concentrationHPOHP:0020061
- Frequent (30% to 79% of cases)
- AnisopoikilocytosisHPOHP:0004823
- Frequent (30% to 79% of cases)
- Decreased total neutrophil countHPOHP:0001875
- Frequent (30% to 79% of cases)
- Oval macrocytosisHPOHP:0032566
- Frequent (30% to 79% of cases)
- PallorHPOHP:0000980
- Frequent (30% to 79% of cases)
- ProteinuriaHPOHP:0000093
- Frequent (30% to 79% of cases)
Show the remaining 18
- ReticulocytosisHPOHP:0001923
- Frequent (30% to 79% of cases)
- Abnormal bleedingHPOHP:0001892
- Occasional (5% to 29% of cases)
- Abnormality of the nervous systemHPOHP:0000707
- Occasional (5% to 29% of cases)
- Angular cheilitisHPOHP:0030318
- Occasional (5% to 29% of cases)
- ConstipationHPOHP:0002019
- Occasional (5% to 29% of cases)
- Delayed ability to walkHPOHP:0031936
- Occasional (5% to 29% of cases)
Genes
2 genes
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
Where it sits
Other names
6 names
Resolves to: Imerslund-Grasbeck syndrome
- Also called
- familial megaloblastic anaemiafamilial megaloblastic anemiaImerslund-Gräsbeck syndromejuvenile megaloblastic Anaemiajuvenile megaloblastic Anemiaselective cobalamin malabsorption with proteinuria