Rare Cardiology News

Disease Profile

Imerslund-Grasbeck syndrome

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

IGS; Pernicious anemia, juvenile, due to selective intestinal malabsorption of vitamin B12, with proteinuria; Enterocyte cobalamin malabsorption;


Blood Diseases; Congenital and Genetic Diseases; Digestive Diseases;


Imerslund-Grasbeck syndrome (IGS) is a rare condition characterized by vitamin B12 deficiency, often causing megaloblastic anemia. IGS usually appears in childhood. Other features may include failure to thrive, infections, and neurological damage. Mild proteinuria (with no signs of kidney disease) is present in about half of affected individuals. IGS is caused by mutations in either the CUBN or AMN gene and is inherited in an autosomal recessive manner. Treatment includes life-long vitamin B12 injections, with which affected individuals can stay healthy for decades.[1]


Affected individuals often first experience non-specific health problems, such as failure to thrive and grow, recurrent gastrointestinal or respiratory infections, pallor and fatigue. Individuals often have anemia, and about half of affected individuals also have mild proteinuria but no signs of kidney disease. Individuals may also have mild neurological damage. Congenital (present at birth) abnormalities of the urinary tract were present in some of the original reported cases. The age at diagnosis is usually anywhere from a few months of age to about 14 years of age.[2][3]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
Childhood onset
Symptoms begin in childhood
Easily confused
Mental disorientation

[ more ]

Dementia, progressive
Progressive dementia

[ more ]

Malabsorption of Vitamin B12
Megaloblastic anemia
Pins and needles feeling

[ more ]

High urine protein levels
Protein in urine

[ more ]

Sensory impairment
Vitamin B12 deficiency


The diagnosis of Imerslund-Grasbeck syndrome (IGS) is made after a series of tests are performed. Cobalamin deficiency is typically detected first, followed by showing that cobalamin is poorly absorbed (the main cause of cobalamin deficiency). Other known causes of vitamin B12 malabsorption must then be ruled out. Lastly, it must be shown that after correcting the deficiency, the only nutrient to be poorly absorbed is vitamin B12. The diagnosis can also be confirmed by having genetic testing of the genes that are known to cause the condition. While the presence of proteinuria is strongly suggestive of IGS, not all affected individuals have proteinuria.[2]

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.


    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

      • Genetics Home Reference (GHR) contains information on Imerslund-Grasbeck syndrome. This website is maintained by the National Library of Medicine.
      • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

        In-Depth Information

        • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
        • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Imerslund-Grasbeck syndrome. Click on the link to view a sample search on this topic.


          1. Grasbeck R. Imerslund-Grasbeck syndrome. Orphanet. May 2006; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=35858. Accessed 7/6/2011.
          2. Ralph Gräsbeck. Imerslund-Gräsbeck syndrome (selective vitamin B12 malabsorption with proteinuria). Orphanet J Rare Dis. May 19, 2006; 1(17):Accessed 1/6/2014.
          3. Ralph Gräsbeck. Gräsbeck-Imerslund disease. Orphanet. May, 2006; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=35858. Accessed 1/6/2014.

          Rare Cardiology News

          fascinating Rare disease knowledge right in your inbox
          Subscribe to receive