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Likely inborn error of metabolism

Gene: CD320

Amber List (moderate evidence)
CD320 (CD320 molecule)
EnsemblGeneIds (GRCh38): ENSG00000167775
EnsemblGeneIds (GRCh37): ENSG00000167775
OMIM: 606475, Gene2Phenotype
CD320 is in 3 panels

2 reviews

Achchuthan Shanmugasundram (Genomics England Curator)

I don't know

Comment on list classification: Although there is sufficient evidence available (at least eight unrelated families) for the association of biallelic CD320 variants with 'Methylmalonic aciduria, transient, due to transcobalamin receptor defect', the reported individuals had no major health or developmental concerns.

As it is a benign condition, this gene is rated amber for now.
Created: 16 Oct 2025, 9:05 a.m. | Last Modified: 16 Oct 2025, 9:05 a.m.
Panel Version: 8.68
The CD320 antigen gene encodes the transcobalamin receptor (TCBLR), which binds transcobalamin (TC) when it is carrying vitamin B12 (cobalamin).

Biallelic variants in this gene are associated with 'Methylmalonic aciduria, transient, due to transcobalamin receptor defect' (MIM #613646) in OMIM (OMIM record accessed on 16 October 2025).

This gene is also associated with 'methylmalonic acidemia due to transcobalamin receptor defect' (MONDO:0013341) with 'definitive' rating by the General Inborn Errors of Metabolism expert panel on ClinGen (https://search.clinicalgenome.org/CCID:004374)
Created: 16 Oct 2025, 8:56 a.m. | Last Modified: 16 Oct 2025, 8:56 a.m.
Panel Version: 8.64

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Methylmalonic aciduria, transient, due to transcobalamin receptor defect, OMIM:613646; methylmalonic acidemia due to transcobalamin receptor defect, MONDO:0013341

Created: 16 Oct 2025, 8:56 a.m.
Last Modified: 16 Oct 2025, 8:56 a.m.
Panel version: 8.64

Sarah Leigh (Genomics England Curator)

gene: CD320 review by Sarah Leigh

Variant rs2336573 associated with serum B12 levels
Created: 23 Feb 2017, 5:12 p.m.
Comment when marking as ready: Associated with phenotype in OMIM, not in G2P / DD. One homozygous variant reported in two cases
Created: 14 Feb 2017, 10:49 a.m.
INTERVENTION/RATIONALE: Treatment with IM vitamin B12 has shown to positively affect laboratory parameters, but long-term clinical sequelae are unclear
Created: 14 Feb 2017, 10:48 a.m.

Mode of inheritance
Unknown

Phenotypes
Methylmalonic aciduria, transient, due to transcobalamin receptor defect 613646

Publications

Created: 23 Feb 2017, 5:12 p.m.

Panel version: Imported from Undiagnosed metabolic disorders panel version 0.304

Details

Mode of Inheritance
BIALLELIC, autosomal or pseudoautosomal
Sources
  • Expert Review Amber
  • London North GLH
  • NHS GMS
Phenotypes
  • Methylmalonic aciduria, transient, due to transcobalamin receptor defect, OMIM:613646
  • methylmalonic acidemia due to transcobalamin receptor defect, MONDO:0013341
OMIM
606475
Clinvar variants
Variants in CD320
Penetrance
None
Publications
Panels with this gene

History Filter Activity

16 Oct 2025, Gel status: 2

Entity classified by Genomics England curator

Achchuthan Shanmugasundram (Genomics England Curator)

Gene: cd320 has been classified as Amber List (Moderate Evidence).

16 Oct 2025, Gel status: 1

Set Phenotypes

Achchuthan Shanmugasundram (Genomics England Curator)

Phenotypes for gene: CD320 were changed from Methylmalonic aciduria due to transcobalamin receptor defect to Methylmalonic aciduria, transient, due to transcobalamin receptor defect, OMIM:613646; methylmalonic acidemia due to transcobalamin receptor defect, MONDO:0013341

16 Oct 2025, Gel status: 1

Set publications

Achchuthan Shanmugasundram (Genomics England Curator)

Publications for gene: CD320 were set to 27604308; 20524213

16 Oct 2025, Gel status: 1

Set mode of inheritance

Achchuthan Shanmugasundram (Genomics England Curator)

Mode of inheritance for gene: CD320 was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal

13 Feb 2019, Gel status: 1

Added New Source, Added New Source

Ivone Leong (Genomics England Curator)

Source NHS GMS was added to CD320. Source London North GLH was added to CD320.

8 Jan 2019, Gel status: 1

Panel promoted to version 1.0

Ellen McDonagh (Genomics England Curator)

Sarah Leigh: Associated with phenotype in O

16 Dec 2018, Gel status: 1

Created, Added New Source, Set mode of inheritance, Set publications, Set Phenotypes

Ellen McDonagh (Genomics England Curator)

gene: CD320 was added gene: CD320 was added to Inborn errors of metabolism. Sources: Expert Review Red Mode of inheritance for gene: CD320 was set to Unknown Publications for gene: CD320 were set to 27604308; 20524213 Phenotypes for gene: CD320 were set to Methylmalonic aciduria due to transcobalamin receptor defect