Details of Disease

General Information of Disease (ID: DIS7B024)

• Disease Name: Methylmalonic acidemia due to transcobalamin receptor defect
• Synonyms: methylmalonic aciduria, transient, due to transcobalamin receptor defect; methylmalonic acidemia, Tcblr type; methylmalonic acidemia, TCbIR type; methylmalonic aciduria due to transcobalamin receptor defect; CD320 methylmalonic acidemia; methylmalonic acidemia, TCb1R type; methylmalonic acidemia caused by mutation in CD320
• Definition: Methylmalonic aciduria due to transcobalamin receptor defect is a rare metabolite absorption and transport disorder characterized by a moderate increase of methylmalonic acid (MMA) in the blood and urine due to decreased cellular uptake of cobalamin resulting from decreased transcobalamin receptor function. Patients are usually asymptomatic however, screening reveals increased C3-acylcarnitine and MMA in plasma. Serum homocysteine levels may vary from normal to moderately elevated and retinal vascular occlusive disease, resulting in severe visual loss, has been reported.
• Disease Hierarchy:
  DISTUC4M: Inborn disorder of cobalamin metabolism and transport
  DISHY8VB: Methylmalonic acidemia
  DIS7B024: Methylmalonic acidemia due to transcobalamin receptor defect
• Disease Identifiers:
  MONDO ID: MONDO_0013341
  UMLS CUI: C4749905
  OMIM ID: 613646
  MedGen ID: 1670056
  Orphanet ID: 280183
  SNOMED CT ID: 771444002

Molecular Interaction Atlas (MIA) of This Disease

This Disease Is Related to 2 DTT Molecule(s)

Gene Name	DTT ID	Evidence Level	Mode of Inheritance	REF
CD320	TT0KV32	Limited	Biomarker	[1]
CD320	TT0KV32	Definitive	Autosomal recessive	[2]

This Disease Is Related to 1 DOT Molecule(s)

Gene Name	DOT ID	Evidence Level	Mode of Inheritance	REF
CD320	OT8CSNU2	Definitive	Autosomal recessive	[2]

References

• [1] Positive newborn screen for methylmalonic aciduria identifies the first mutation in TCblR/CD320, the gene for cellular uptake of transcobalamin-bound vitamin B(12). Hum Mutat. 2010 Aug;31(8):924-9. doi: 10.1002/humu.21297.
• [2] Technical standards for the interpretation and reporting of constitutional copy-number variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics (ACMG) and the Clinical Genome Resource (ClinGen). Genet Med. 2020 Feb;22(2):245-257. doi: 10.1038/s41436-019-0686-8. Epub 2019 Nov 6.