Gene
The D2HGDH gene (D-2-hydroxyglutarate dehydrogenase) is located on chromosome 2q37.1 in the human genome. It spans approximately 50 kilobases and comprises 11 exons. The reference mRNA (NM_001130860) encodes a protein of 475 amino acids.
Protein
The protein product of D2HGDH is a mitochondrial flavoprotein that belongs to the D-2-hydroxyglutarate dehydrogenase family. It contains an N‑terminal mitochondrial targeting sequence, a conserved FAD‑binding domain, and a C‑terminal catalytic domain. The mature enzyme resides in the mitochondrial matrix.
Biochemical Function
D-2-hydroxyglutarate dehydrogenase catalyzes the oxidation of D‑2‑hydroxyglutarate (D‑2HG) to α‑ketoglutarate (α‑KG) using flavin adenine dinucleotide (FAD) as a cofactor. This reaction is part of the low‑level catabolism of D‑2HG, a metabolite that can accumulate in certain metabolic and oncogenic contexts. By converting D‑2HG to α‑KG, the enzyme helps maintain cellular redox balance and supports the tricarboxylate cycle.
Clinical Significance
Pathogenic variants in D2HGDH cause D-2-hydroxyglutaric aciduria type I, an autosomal‑recessive metabolic disorder characterized by:
- Elevated concentrations of D‑2HG in urine, plasma, and cerebrospinal fluid.
- Neurological manifestations, including developmental delay, seizures, and ataxia.
- Variable neuroimaging findings, often showing cerebral white‑matter abnormalities.
The disorder is distinct from D-2-hydroxyglutaric aciduria type II, which results from mutations in L2HGDH (the enzyme that degrades L‑2‑hydroxyglutarate).
Genotype–Phenotype Correlation
Most reported disease‑causing mutations are missense, nonsense, or splice‑site variants that lead to loss of enzymatic activity. Functional studies of recombinant mutant proteins demonstrate reduced or absent conversion of D‑2HG to α‑KG.
Research and Therapeutic Context
D2HGDH activity has also been examined in oncology because elevated D‑2HG is a hallmark of tumors harboring gain‑of‑function mutations in the isocitrate dehydrogenase genes (IDH1/IDH2). While D2HGDH itself is not commonly mutated in cancer, its role in clearing D‑2HG positions it as a potential target for metabolic modulation.
Protein Interactions
Current protein‑interaction databases list mitochondrial matrix proteins involved in the tricarboxylate cycle (e.g., malate dehydrogenase, succinate dehydrogenase) as putative interaction partners, reflecting shared subcellular localization rather than direct functional complexes.
References
- Entrez Gene: D2HGDH D-2-hydroxyglutarate dehydrogenase. National Center for Biotechnology Information.
- Struys, E. A., et al. (2008). “D-2-hydroxyglutaric aciduria, an inborn error of metabolism.” Molecular Genetics and Metabolism, 94(3), 191‑197.
- Zhao, S., et al. (2012). “Loss of D-2-hydroxyglutarate dehydrogenase in human cancers.” Journal of Clinical Investigation, 122(6), 2417‑2426.
Note: All information reflects current scientific consensus as documented in peer‑reviewed biomedical literature and reputable genomic databases.
