CD320 encodes CD320 molecule (282 aa). Receptor for transcobalamin saturated with cobalamin (TCbl). Plays an important role in cobalamin uptake. Highest expression in Testis (83.8 TPM) and Cells Cultured fibroblasts (63.7 TPM).

Methylmalonic acidemia due to transcobalamin receptor defect is caused by mutations in the CD320 gene on chromosome 19.

The CD320 protein participates in Defective CD320 causes MMATC, Defective CD320 does not transport extracellular TCII:Cbl to endosome, and CD320-mediated TCN2:RCbl uptake and delivery to lysosome pathways.

CD320 is classified as a druggable target (Druggable Genome and Growth Factor categories) with score 0.0.

Genetic testing for CD320 is available. Testing is considered confirmatory for diagnosis.

Biomarker and diagnostic research for methylmalonic acidemia due to transcobalamin receptor defect has been reported in the published literature.

Phenotype severity distribution: 3 always present features, 1 common feature.

Estimated prevalence: <1 in 1,000,000 (VERY_RARE).

No clinical trials have been registered for methylmalonic acidemia due to transcobalamin receptor defect.

3 publications have been identified in PubMed for methylmalonic acidemia due to transcobalamin receptor defect. Research spans Diagnostic / Biomarker (33%), Review / Meta-Analysis (33%), and Epidemiology / Natural History (33%).

Recent Publications

• Fecarotta S (2025). [PMID: 39856690](https://pubmed.ncbi.nlm.nih.gov/39856690/). *Orphanet journal of rare diseases*. [Epidemiology / Natural History]

• Mucha P (2024). [PMID: 39125597](https://pubmed.ncbi.nlm.nih.gov/39125597/). *International journal of molecular sciences*. [Review / Meta-Analysis]

• Veldman A (2024). [PMID: 39846587](https://pubmed.ncbi.nlm.nih.gov/39846587/). *International journal of neonatal screening*. [Diagnostic / Biomarker]