GENE REFERENCE / HGNC:2548

CUBN

cubilin

protein-coding gene10p13Gene information

What does this gene do?

The CUBN gene provides instructions for making a protein called cubilin. This protein helps the body absorb vitamin B12 (also called cobalamin) from food, which is important because the body cannot make this vitamin. Vitamin B12 is essential for the formation of DNA and for the chemical reactions that convert food into energy (energy metabolism). Vitamin B12 also plays a key role in making red blood cells and maintaining the nerve cells in the brain and spinal cord (central nervous system).

Cubilin binds to another protein called amnionless to form a complex called the cubam receptor, which is present in the kidneys and the small intestine. In the small intestine, cubilin interacts with vitamin B12 while it is anchored to the cell membrane by amnionless.

During digestion, vitamin B12 binds to intrinsic factor, which helps the intestines absorb vitamin B12. Vitamin B12 and intrinsic factor then bind to cubilin as they pass through the small intestine. Amnionless helps transfer this whole complex into the intestinal cells. Vitamin B12 is then released into the blood and travels throughout the body. In the kidneys, amnionless and cubilin help return proteins to the bloodstream (reabsorption) that would otherwise be released in the urine.

Source: MedlinePlus, National Library of Medicine. Source publication: 2026-04-09. Source review: 2026-04.

ClinGen reviews

We found no matching ClinGen review in the data used here. This does not rule out a link between the gene and a condition.

ClinVar records

These numbers show what has been submitted to ClinVar. They cannot tell you how likely you are to have a condition.

Submitted alleles: 2,698
Submissions for variants in or overlapping this gene: 4,669
Submissions explicitly reporting this gene: 4,571
Alleles reported pathogenic / likely pathogenic: 229
VariationIDs with uncertain significance: 1,278
VariationIDs with conflicting classifications: 149

The rows count different things: alleles, submissions or VariationIDs. Their categories can overlap, so do not add them together. Pathogenic/likely pathogenic counts exclude structural variants that merely overlap a gene. A dash in the source means “not reported,” not zero.

NCBI produces the gene-summary file each week using counts recorded at the start of the month. The numbers may differ from those on the live ClinVar website. Read the field definitions ↗

View this gene in ClinVar ↗

YOUR DNA FILE

Can your DNA file tell you about CUBN?

From a DNA test kit (such as 23andMe, AncestryDNA or MyHeritage). These kits check a fixed list of about 600,000 to 700,000 positions across your whole genome. ClinVar lists 229 alleles in CUBN reported as pathogenic or likely pathogenic. A kit checks only some of these positions, and often none of them.

From whole genome sequencing (a VCF file). Sequencing reads most of your genome. Your file lists the places where your DNA differs from the reference genome. Some regions are hard to sequence, including parts of some genes that have near-identical copies elsewhere, and a VCF file does not record which positions were read well.

If a variant is not in your file, that does not mean you don’t have it.

What BioDecode checks

BioDecode compares every variant in your file with ClinVar, on your own computer. For each match, it shows the ClinVar classification, the review status and the condition it was reported for. Your file is not uploaded.

A ClinVar classification applies to one particular variant and the condition it was reported for. It does not tell you about other variants in CUBN.

BioDecode cannot fill gaps in your test, diagnose a condition or replace clinical testing.

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