Succinic acidemia
suh-SIN-ik ah-sid-EE-mee-uh
Also known as: Succinic aciduria, Succinic acid metabolic disorder
At a Glance
What is Succinic acidemia?
Succinic acidemia is a rare metabolic disorder where the body cannot properly process succinic acid, leading to its accumulation. This condition primarily affects the metabolic system, but can have widespread effects on other body systems. It is caused by a deficiency in the enzyme responsible for breaking down succinic acid. Over time, the accumulation of succinic acid can lead to severe metabolic acidosis. Early symptoms may include poor feeding, vomiting, and lethargy, while late symptoms can progress to developmental delays and neurological issues. Early diagnosis is critical to manage symptoms and prevent severe complications. The condition can place a significant emotional and financial burden on families. Prognosis varies, but early intervention can improve outcomes. Daily life for affected individuals often involves regular medical monitoring and dietary management. Treatment may include dietary restrictions and supplements to manage acid levels. Supportive therapies, such as physical and occupational therapy, can help manage developmental delays. Genetic counseling is recommended for families.
Medical Definition
Succinic acidemia is characterized by an abnormal accumulation of succinic acid due to a deficiency in the enzyme succinate dehydrogenase. Pathologically, this leads to metabolic acidosis and potential damage to various organs. Histological findings may include mitochondrial abnormalities in affected tissues. It is classified under organic acidemias, a group of metabolic disorders. The epidemiology of succinic acidemia is not well-documented due to its rarity. The disease course can vary, with some individuals experiencing severe symptoms early in life, while others may have a milder progression.
Succinic acidemia Symptoms
Symptoms vary in severity between individuals. Early diagnosis and management can significantly improve outcomes.
Very Common
Lactic acidosis manifests as an accumulation of lactic acid in the body, leading to symptoms such as rapid breathing, nausea, and abdominal pain. It is caused by a deficiency in the enzyme NADH-cytochrome c reductase, which impairs the electron transport chain and energy production in cells. Over time, lactic acidosis can lead to severe metabolic imbalances and organ dysfunction if not managed promptly. Patients may experience fatigue and muscle weakness, and management includes supportive care and addressing the underlying metabolic defect.
Developmental delay is characterized by a slower rate of achieving developmental milestones such as walking, talking, and social interaction. This occurs due to the impaired energy metabolism affecting brain development and function. Without intervention, the delay can become more pronounced, impacting cognitive and motor skills. Early intervention with therapies can help improve outcomes and assist in achieving developmental goals.
Hypotonia, or decreased muscle tone, presents as floppy limbs and difficulty with motor activities. It results from impaired energy production in muscle cells due to the enzyme deficiency. Over time, hypotonia can lead to joint instability and difficulties with movement and posture. Physical therapy and supportive devices can help manage symptoms and improve muscle strength.
Common
Failure to thrive is observed as poor weight gain and growth in infants and children. It is caused by the body's inability to efficiently produce energy, leading to inadequate nutrition utilization. If not addressed, it can result in stunted growth and developmental issues. Nutritional support and metabolic management are crucial to promote normal growth patterns.
Seizures occur as episodes of abnormal electrical activity in the brain, leading to convulsions or altered consciousness. The energy deficit in brain cells due to the metabolic disorder can trigger these episodes. Seizures may become more frequent and severe without appropriate treatment. Antiepileptic medications and metabolic control are essential to manage and reduce seizure frequency.
Vomiting is a frequent symptom, often occurring after feeding, and can lead to dehydration and electrolyte imbalances. It is a result of metabolic disturbances and the body's response to the accumulation of toxic metabolites. Persistent vomiting can affect nutritional status and growth if not managed. Anti-emetic medications and dietary adjustments can help alleviate this symptom.
Less Common
Hepatomegaly, or enlarged liver, can be detected during a physical examination as an increase in liver size. It is caused by the accumulation of metabolites and stress on the liver due to impaired metabolism. Over time, hepatomegaly can lead to liver dysfunction if not monitored. Regular liver function tests and supportive care are important to manage liver health.
Cardiomyopathy presents as a weakened heart muscle, leading to symptoms such as fatigue, shortness of breath, and swelling of the extremities. The energy production deficit affects heart muscle cells, impairing their function. If untreated, it can progress to heart failure and significantly impact quality of life. Management includes medications to support heart function and regular cardiac monitoring.
What Causes Succinic acidemia?
Succinic acidemia is linked to mutations in the SDHA gene located on chromosome 5p15.33. The SDHA gene encodes the succinate dehydrogenase complex subunit A, a key component of the mitochondrial respiratory chain. Mutations in SDHA can lead to structural changes in the protein, impairing its ability to participate in electron transport. This disruption results in decreased NADH-cytochrome c reductase activity, leading to an accumulation of succinic acid. The buildup of succinic acid causes mitochondrial dysfunction, affecting cellular energy production. Neighboring cells experience oxidative stress due to the imbalance in reactive oxygen species. Neuroinflammation may be triggered as a response to cellular stress, exacerbating neuronal damage. Over time, this can lead to the degeneration of white matter and other neural structures. Symptoms manifest as neurological deficits, often presenting as developmental delays and seizures. The pattern of symptoms is influenced by the specific neural circuits affected by mitochondrial dysfunction. Variability in disease severity among patients may be due to differences in residual enzyme activity or compensatory metabolic pathways. Additionally, genetic modifiers and environmental factors can influence the clinical presentation. The immune system's response to cellular damage may further contribute to symptom variability. Understanding these mechanisms is crucial for developing targeted therapies. Continued research is needed to fully elucidate the pathophysiology of succinic acidemia.
How is Succinic acidemia Diagnosed?
Typical age of diagnosis: Succinic acidemia is typically diagnosed in infancy or early childhood when symptoms such as developmental delay, metabolic acidosis, and failure to thrive become apparent. Diagnosis often follows a combination of clinical suspicion and laboratory findings indicative of metabolic dysfunction.
The clinician looks for signs of metabolic acidosis, developmental delay, and failure to thrive. A detailed family history is taken to identify any genetic predisposition or similar symptoms in relatives. Physical examination may reveal hypotonia, poor feeding, and lethargy. This step helps to narrow down the differential diagnosis to metabolic disorders.
Magnetic Resonance Imaging (MRI) of the brain is commonly used. Specific abnormalities such as cerebral atrophy or delayed myelination may be visible. These findings support the diagnosis by correlating clinical symptoms with structural brain changes. Imaging also helps exclude other neurological conditions like leukodystrophies.
Blood and urine tests are ordered to measure organic acids, particularly elevated levels of succinic acid. Biomarkers such as lactic acid and pyruvate may also be elevated. Abnormal results show increased organic acids and decreased NADH-cytochrome c reductase activity. These results guide further genetic testing and management strategies.
Genes involved in mitochondrial function, such as those encoding components of the electron transport chain, are sequenced. Mutations such as point mutations or deletions are identified. Results confirm the diagnosis by correlating genetic abnormalities with biochemical findings. Genetic testing informs family counseling regarding inheritance patterns and recurrence risks.
Succinic acidemia Treatment Options
Carnitine is a supplement that aids in the transport of fatty acids into mitochondria. It helps improve energy production by facilitating the oxidation of fatty acids. Specific drugs used include L-carnitine supplements. Clinical evidence suggests it can reduce symptoms of fatigue and improve metabolic profiles. Limitations include gastrointestinal side effects and the need for regular monitoring of blood levels.
Techniques such as motor skill exercises and balance training are used. The goal is to improve muscle tone, coordination, and overall physical development. Sessions are typically conducted 2-3 times per week for 30-60 minutes. Measurable outcomes include improved gross motor skills and increased muscle strength. Long-term benefits include enhanced quality of life and increased independence.
Indicated for children with severe feeding difficulties and failure to thrive. The procedure involves placing a tube directly into the stomach for nutritional support. Expected benefits include improved nutritional intake and growth. Surgical risks include infection and tube displacement. Post-operative care involves regular cleaning and monitoring for complications.
The team includes a metabolic specialist, nutritionist, physical therapist, and psychologist. Interventions focus on nutritional support, developmental therapies, and metabolic crisis management. Psychosocial support strategies involve counseling and support groups for families. Family education covers disease management and emergency protocols. Long-term monitoring includes regular follow-up visits and adjustment of care plans as needed.
When to See a Doctor for Succinic acidemia
- Severe metabolic acidosis — this is an emergency because it can lead to life-threatening complications if not treated promptly.
- Unresponsive or altered mental status — this indicates potential severe metabolic imbalance requiring immediate medical attention.
- Severe dehydration or shock — these conditions can rapidly deteriorate and require urgent intervention.
- Persistent vomiting — this can lead to dehydration and electrolyte imbalance, and a doctor should be consulted for management.
- Failure to thrive or poor weight gain in infants — this may indicate metabolic issues needing further investigation.
- Recurrent infections — these could suggest an underlying metabolic disorder that requires medical evaluation.
- Mild fatigue — monitor energy levels and ensure adequate nutrition and hydration.
- Occasional mild headaches — keep track of frequency and severity, and consult a doctor if they worsen.
Succinic acidemia — Frequently Asked Questions
Is this condition hereditary?
Succinic acidemia is typically inherited in an autosomal recessive pattern, meaning both parents must carry one copy of the mutated gene. The probability of passing the condition to children is 25% if both parents are carriers. De novo mutations are rare but possible. Carrier status does not usually affect health but genetic counseling is recommended for family planning. Genetic counseling can provide information on risks and testing options.
What is the life expectancy for someone with this condition?
Life expectancy varies depending on the age of onset and severity of symptoms. Early diagnosis and management can improve outcomes significantly. Mortality is often due to metabolic crises or complications such as organ failure. Treatment, including dietary management and supplements, can enhance survival and quality of life. Realistic expectations should include ongoing medical care and monitoring.
How is this condition diagnosed and how long does diagnosis take?
Diagnosis involves metabolic screening and genetic testing to identify specific enzyme deficiencies. The time from first symptoms to diagnosis can vary, often taking weeks to months. Specialists such as geneticists and metabolic disorder experts are typically consulted. Delayed diagnosis may occur due to symptom overlap with other conditions. Confirmation is achieved through laboratory tests showing elevated succinic acid levels.
Are there any new treatments or clinical trials available?
Current research is exploring enzyme replacement therapies and gene therapy as potential treatments. Novel approaches aim to correct the underlying metabolic defect. ClinicalTrials.gov is a resource for finding ongoing trials related to succinic acidemia. Discussing trial eligibility and potential benefits with your doctor is crucial. New treatments may take several years to become widely available.
How does this condition affect daily life and activities?
Succinic acidemia can impact mobility and self-care, particularly during metabolic crises. Educational support may be necessary due to cognitive or developmental delays. Social and emotional challenges include coping with chronic illness and potential isolation. Family burden can be significant, requiring support and respite care. Adaptations such as dietary management and therapy can help improve quality of life.
Support & Resources
References
Content generated with support from peer-reviewed literature via PubMed.
- 1.Succinic acidemia: a new syndrome of organic acidemia associated with congenital lactic acidosis and decreased NADH-cytochrome c reductase activity.
Asano K, Miyamoto I, Matsushita T et al. · Clin Chim Acta · 1988 · PMID: 3383430
- 2.Succinic acidemia is not a new syndrome of organic acidemia.
Elpeleg ON, Hurvitz H · Clin Chim Acta · 1990 · PMID: 2387080
This content is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.Last reviewed: 2026-05-02