U.S. flag

An official website of the United States government


Send to:

Choose Destination

Mitochondrial complex II deficiency, nuclear type 1(MC2DN1)

MedGen UID:
Concept ID:
Disease or Syndrome
Synonyms: Complex 2 mitochondrial respiratory chain deficiency; Mitochondrial complex II deficiency; Mitochondrial Respiratory Chain Complex II Deficiency; Mitochondrial Respiratory Chain Complex II Deficiency, SDHA-Related; Mitochondrial Respiratory Chain Complex II Deficiency, SDHAF1-Related; Succinate CoQ reductase deficiency
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
Concept ID:
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
Gene (location): SDHA (5p15.33)
Monarch Initiative: MONDO:0100294
OMIM®: 252011
Orphanet: ORPHA3208


Mitochondrial complex II deficiency is an autosomal recessive multisystemic metabolic disorder with a highly variable phenotype. Some patients have multisystem involvement of the brain, heart, and muscle with onset in infancy, whereas others have only isolated cardiac or muscle involvement. Measurement of complex II activity in muscle is the most reliable means of diagnosis; however, there is no clear correlation between residual complex II activity and severity or clinical outcome. In some cases, treatment with riboflavin may have clinical benefit (summary by Jain-Ghai et al., 2013). Complex II, also known as succinate dehydrogenase, is part of the mitochondrial respiratory chain. Genetic Heterogeneity of Mitochondrial Complex II Deficiency See MC2DN2 (619166), caused by mutation in the SDHAF1 gene (612848) on chromosome 19q13; MC2DN3 (619167), caused by mutation in the SDHD gene (602690) on chromosome 11q23; and MC2DN4 (619224), caused by mutation in the SDHB gene (185470) on chromosome 1p36. Fullerton et al. (2020) reviewed the genetic basis of isolated mitochondrial complex II deficiency. [from OMIM]

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  

Supplemental Content

Recent activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...