mitochondrial DNA depletion syndrome 9

MONDO:0009504Mondo

Findings

No curated finding names mitochondrial DNA depletion syndrome 9 yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.

Fatal infantile lactic acidosis with methylmalonic aciduria is a rare neurometabolic disease characterized by infantile onset of severe encephalomyopathy, lactic acidosis and elevated methylmalonic acid urinary excretion. Clinically it manifests with severe psychomotor delay, hypotonia, failure to thrive, feeding difficulties and dystonia. Epilepsy and multiple congenital anomalies may be associated.

Definition from the Mondo Disease Ontology (MONDO:0009504), read 2026-09-29. CC BY 4.0.

Inheritance: Autosomal recessive inheritance
Onset and course: Death in infancy · Infantile onset · Neonatal onset · Neonatal death · Death in childhood

Features

86 features

What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.

AreflexiaHPOHP:0001284
- 1 of 1 reported patient
Axial hypotoniaHPOHP:0008936
- 1 of 1 reported patient
Elevated circulating alanine aminotransferase concentrationHPOHP:0031964
- 1 of 1 reported patient
Elevated circulating aspartate aminotransferase concentrationHPOHP:0031956
- 1 of 1 reported patient
Elevated lactate:pyruvate ratioHPOHP:0032653
- 3 of 3 reported patients
Feeding difficultiesHPO

Genes

1 gene

Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.

SUCLG1HGNC:11449
- Definitive · G2P · Autosomal recessive · 2015
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2022
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021

Where it sits

A kind of: lactic acidosis
mitochondrial DNA depletion syndrome, encephalomyopathic form

Other names

3 names

Resolves to: mitochondrial DNA depletion syndrome 9

Also called: mitochondrial DNA depletion syndrome caused by mutation in SUCLG1mitochondrial DNA depletion syndrome type 9SUCLG1 mitochondrial DNA depletion syndrome

Show the remaining 74

HypotoniaHPOHP:0001252
- 3 of 3 reported patients · Neonatal onset
Increased CSF lactateHPOHP:0002490
- 1 of 1 reported patient
- Frequent (30% to 79% of cases)
Lactic acidosisHPOHP:0003128
- 3 of 3 reported patients · Neonatal onset
- 1 of 1 reported patient
- 2 of 2 reported patients
- Frequent (30% to 79% of cases)
LacticaciduriaHPOHP:0003648
- 3 of 3 reported patients · Neonatal onset
Methylmalonic acidemiaHPOHP:0002912
- Obligate (100% of cases)
Methylmalonic aciduriaHPOHP:0012120
- 3 of 3 reported patients · Neonatal onset
- 1 of 1 reported patient
- 2 of 2 reported patients
- Obligate (100% of cases)
Motor delayHPOHP:0001270
- 1 of 1 reported patient
Persistent head lagHPOHP:0032988
- 1 of 1 reported patient
Poor head controlHPOHP:0002421
- 1 of 1 reported patient
Severe intellectual disabilityHPOHP:0010864
- 1 of 1 reported patient
3-Methylglutaconic aciduriaHPOHP:0003535
- Very frequent (80% to 99% of cases)
Abnormal basal ganglia MRI signal intensityHPOHP:0012751
- Very frequent (80% to 99% of cases)
Abnormal circulating enzyme concentration or activityHPOHP:0012379
- Very frequent (80% to 99% of cases)
Global developmental delayHPOHP:0001263
- Very frequent (80% to 99% of cases)
Intrauterine growth retardationHPOHP:0001511
- 2 of 3 reported patients · Fetal onset
Cerebral atrophyHPOHP:0002059
- Frequent (30% to 79% of cases)
Decreased activity of mitochondrial complex IHPOHP:0011923
- Frequent (30% to 79% of cases)
Decreased activity of mitochondrial complex IIIHPOHP:0011924
- Frequent (30% to 79% of cases)
Decreased activity of mitochondrial complex IVHPOHP:0008347
- Frequent (30% to 79% of cases)
Elevated circulating hepatic transaminase concentrationHPOHP:0002910
- Frequent (30% to 79% of cases)
EncephalopathyHPOHP:0001298
- Frequent (30% to 79% of cases)
Failure to thriveHPOHP:0001508
- Frequent (30% to 79% of cases)
Growth delayHPOHP:0001510
- Frequent (30% to 79% of cases)
Hepatic steatosisHPOHP:0001397
- Frequent (30% to 79% of cases)
HepatomegalyHPOHP:0002240
- Frequent (30% to 79% of cases)
Increased circulating lactate concentrationHPOHP:0002151
- Frequent (30% to 79% of cases)
Intellectual disabilityHPOHP:0001249
- Frequent (30% to 79% of cases)
Skeletal muscle atrophyHPOHP:0003202
- Frequent (30% to 79% of cases)
Focal T2 hyperintense basal ganglia lesionHPOHP:0007183
- 1 of 2 reported patients
Abnormal mitochondrial shapeHPOHP:0012087
- Occasional (5% to 29% of cases)
Aggressive behaviorHPOHP:0000718
- Occasional (5% to 29% of cases)
ApneaHPOHP:0002104
- Occasional (5% to 29% of cases)
ChoreoathetosisHPOHP:0001266
- Occasional (5% to 29% of cases)
DystoniaHPOHP:0001332
- Occasional (5% to 29% of cases)
Flexion contractureHPOHP:0001371
- Occasional (5% to 29% of cases)
Gastroesophageal refluxHPOHP:0002020
- Occasional (5% to 29% of cases)
Hyperkinetic movementsHPOHP:0002487
- Occasional (5% to 29% of cases)
HypertoniaHPOHP:0001276
- Occasional (5% to 29% of cases)
Hypertrophic cardiomyopathyHPOHP:0001639
- Occasional (5% to 29% of cases)
Increased intramyocellular lipid dropletsHPOHP:0012240
- Occasional (5% to 29% of cases)
Increased variability in muscle fiber diameterHPOHP:0003557
- Occasional (5% to 29% of cases)
LeukoencephalopathyHPOHP:0002352
- Occasional (5% to 29% of cases)
MicrocephalyHPOHP:0000252
- Occasional (5% to 29% of cases)
MyoclonusHPOHP:0001336
- Occasional (5% to 29% of cases)
PtosisHPOHP:0000508
- Occasional (5% to 29% of cases)
Ragged-red muscle fibersHPOHP:0003200
- Occasional (5% to 29% of cases)
Recurrent respiratory infectionsHPOHP:0002205
- Occasional (5% to 29% of cases)
Respiratory distressHPOHP:0002098
- Occasional (5% to 29% of cases)
RhabdomyolysisHPOHP:0003201
- Occasional (5% to 29% of cases)
SeizureHPOHP:0001250
- Occasional (5% to 29% of cases)
Sensorineural hearing impairmentHPOHP:0000407
- Occasional (5% to 29% of cases)
Short attention spanHPOHP:0000736
- Occasional (5% to 29% of cases)
Sleep disturbanceHPOHP:0002360
- Occasional (5% to 29% of cases)
StrabismusHPOHP:0000486
- Occasional (5% to 29% of cases)
Unsteady gaitHPOHP:0002317
- Occasional (5% to 29% of cases)
VomitingHPOHP:0002013
- Occasional (5% to 29% of cases)
Abnormal renal collecting system morphologyHPOHP:0004742
- Very rare (1% to 4% of cases)
Coarctation of aortaHPOHP:0001680
- Very rare (1% to 4% of cases)
Ethylmalonic aciduriaHPOHP:0003219
- Very rare (1% to 4% of cases)
HypospadiasHPOHP:0000047
- Very rare (1% to 4% of cases)
Interrupted aortic archHPOHP:0011611
- Very rare (1% to 4% of cases)
Orofacial cleftHPOHP:0000202
- Very rare (1% to 4% of cases)
Patent ductus arteriosusHPOHP:0001643
- Very rare (1% to 4% of cases)
Patent foramen ovaleHPOHP:0001655
- Very rare (1% to 4% of cases)
PolydactylyHPOHP:0010442
- Very rare (1% to 4% of cases)
Short femurHPOHP:0003097
- Very rare (1% to 4% of cases)
Short humerusHPOHP:0005792
- Very rare (1% to 4% of cases)
Depletion of mitochondrial DNA in muscle tissueHPOHP:0009141
Elevated brain lactate level by MRSHPOHP:0012707
HyperglycinemiaHPOHP:0002154
HypertaurinemiaHPOHP:0500181
Neonatal respiratory distressHPOHP:0002643
Respiratory failureHPOHP:0002878
Respiratory insufficiencyHPOHP:0002093