SUCLA2-related mitochondrial DNA depletion syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

SUCLA2-related mitochondrial DNA (mtDNA) depletion syndrome is an inherited disorder that affects the early development of the brain. Affected infants typically develop weak muscle tone (hypotonia) in the first few months of life. In these infants, hypotonia can delay the development of motor skills such as lifting the head and rolling over. Children with SUCLA2-related mtDNA depletion syndrome typically have difficulty eating and may require a feeding tube; as a result, they have difficulty growing and gaining weight as expected (failure to thrive).

Additional features of SUCLA2-related mtDNA depletion syndrome can include uncontrolled movements (dystonia), hearing loss, muscle wasting (atrophy), and intellectual disabilities. In most affected children, a substance called methylmalonic acid builds up in the blood.

People with SUCLA2-related mtDNA depletion syndrome typically have a shortened lifespan. Approximately 30 percent of individuals with SUCLA2-related mtDNA depletion syndrome do not survive past childhood.

Inheritance

From: MedlinePlus Genetics, National Library of Medicine

Autosomal recessive

Understanding terms used in the source

These definitions explain medical words used above. A definition is not evidence that another condition is present, and it does not predict how a symptom will develop. Ask the clinician which terms apply to the actual examination or test result.

Failure to thrive

Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.

Hypotonia

Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.

Affected

This term applies to a family member who is diagnosed with the same condition as the individual who is the primary focus of investigation (the proband).

Dystonia

An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk.

When it may begin

From: MedlinePlus Genetics, National Library of Medicine

Affected infants typically develop weak muscle tone (hypotonia) in the first few months of life. In these infants, hypotonia can delay the development of motor skills such as lifting the head and rolling over. Approximately 30 percent of individuals with SUCLA2-related mtDNA depletion syndrome do not survive past childhood.

Inheritance in the source

From: MedlinePlus Genetics, National Library of Medicine

Autosomal recessive

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing SUCLA2-related mitochondrial DNA depletion syndrome is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for SUCLA2-related mitochondrial DNA depletion syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.