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Gene

TCN2

transcobalamin 2

Summary

Cytogenetic location
22q12.2
Coordinates
Chromosome 22: 30,607,174–30,627,271 (GRCh38)
Exons
9 exons across 20.1 kb
Protein
427 amino acids
Inheritance
Autosomal recessive
Also known as
D22S676, D22S750, TC2
MANE Select transcript
ENST00000215838.8NM_000355.4
Locus type
gene with protein product
  • Very high
  • Confident
  • Low
  • Very low

Reference genomeGRCh38

Positions on gene and variant pages follow this choice, in this browser.

Curated report relevant to this gene

  • Homocystinuria & Cobalamin Disorders

    • Inborn Disorders of Cobalamin Metabolism and TransportAutosomal recessive

      Includes defects in vitamin B12 absorption and transport such as Imerslund-Gräsbeck syndrome (CUBN, AMN), intrinsic factor deficiency (CBLIF) and transcobalamin II deficiency (TCN2), as well as intracellular cobalamin processing defects, which can cause megaloblastic anaemia, nerve damage and failure to thrive.

      • ClinGen rates the link definitive
      • 5 GenCC submitters rate it definitive or strong
      What knowing changes

      Knowing allows lifelong vitamin B12 injections or other cobalamin treatment, which can prevent anaemia and neurological damage.

Inheritance

Autosomal recessive
It takes a changed copy from each parent. With one, you are a carrier and usually unaffected; when both parents are carriers, each child has a one-in-four chance of inheriting two.

How TCN2 is laid out

  • Coding sequence
  • Untranslated region
  • Intron
  • Direction of transcription
  • Known disease-causing sites
  • Stretches short reads find hard
Chromosome 22, with a bracket where TCN2 sits. TCN2 and 24 genes near it on chromosome 22, from 30,117,223 to 31,117,222.Chromosome 2222q12.2p13p12p11.2p11.1q11.1q11.21q11.22q11.23q12.1q12.2q12.3q13.1q13.2q13.31q13.32q13.3330.2 Mb30.4 Mb30.6 Mb30.8 Mb31 MbHORMAD2: 30,080,444–30,211,427, forward strandHORMAD2LIF: 30,240,453–30,246,804, reverse strandLIFOSM: 30,262,829–30,266,858, reverse strandOSMCASTOR1: 30,285,114–30,289,694, reverse strandCASTOR1: 30,285,238–30,299,482, reverse strandTBC1D10A: 30,291,990–30,326,947, reverse strandTBC1D10ASF3A1: 30,331,988–30,356,919, reverse strandSF3A1CCDC157: 30,356,631–30,378,673, forward strandCCDC157RNF215: 30,368,811–30,421,771, reverse strandSEC14L2: 30,396,941–30,425,303, forward strandSEC14L2: 30,409,255–30,428,990, forward strandMTFP1: 30,425,623–30,429,058, forward strandMTFP1SEC14L3: 30,447,959–30,472,056, reverse strandSEC14L3SEC14L4: 30,488,890–30,505,725, reverse strandSEC14L4SEC14L6: 30,522,799–30,546,741, reverse strandSEC14L6GAL3ST1: 30,554,632–30,576,210, reverse strandGAL3ST1PES1: 30,576,624–30,607,083, reverse strandPES1TCN2: 30,607,174–30,627,271, forward strandTCN2SLC35E4: 30,635,673–30,669,016, forward strandSLC35E4DUSP18: 30,652,051–30,667,887, reverse strandDUSP18OSBP2: 30,693,782–30,907,824, forward strandOSBP2MORC2: 30,925,130–30,969,662, reverse strandMORC2TUG1: 30,969,245–30,979,413, forward strandTUG1SMTN: 31,064,105–31,104,757, forward strandSMTNSELENOM: 31,104,772–31,120,069, reverse strandSELENOMDiagram of TCN2: 9 exons on the forward strand of chromosome 22Exon 1: 2 known disease-causing sitesExon 2: 7 known disease-causing sitesExon 3: 11 known disease-causing sitesExon 4: 5 known disease-causing sitesExon 5: 6 known disease-causing sitesExon 6: 8 known disease-causing sitesExon 7: 7 known disease-causing sitesExon 8: 6 known disease-causing sitesExon 1: 30,607,174–30,607,395, 222 basesExon 2: 30,610,871–30,611,063, 193 basesExon 3: 30,612,873–30,613,042, 170 basesExon 4: 30,614,349–30,614,501, 153 basesExon 5: 30,615,301–30,615,473, 173 basesExon 6: 30,615,601–30,615,787, 187 basesExon 7: 30,617,330–30,617,495, 166 basesExon 8: 30,622,968–30,623,083, 116 basesExon 9: 30,626,460–30,627,271, 812 bases1246895′3′

Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.

Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).

Nearby genes from Ensembl release 116, on GRCh38.

Exons make up 2.2 kb of the gene's 20.1 kb; 1,284 of those bases code for the protein.

How a genome test reads TCN2

62

positions in TCN2 where ClinVar classes a change as pathogenic or likely pathogenic

None of them falls in a region short reads find hard.

A whole genome covers all 20.1 kb of TCN2, introns included, not only the 2.2 kb of exons.

Where this comes from

  • HGNC: the gene's symbol, name, other symbols and location.
  • MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
  • GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
  • The ACMG secondary findings list, SF v3.2.
  • ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
  • The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
  • Data release 2026.10.16-c6eea6bf.

Cite this page

APA

Dante Labs. (n.d.). TCN2 gene: transcobalamin 2. Retrieved 16 October 2026, from https://dantelabs.com/genes/tcn2

Vancouver

Dante Labs. TCN2 gene: transcobalamin 2 [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/tcn2

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