Combined oxidative phosphorylation defect type 13

What it is

From: Orphanet

Combined oxidative phosphorylation defect type 13 is a rare mitochondrial disease due to a defect in mitochondrial protein synthesis characterized by normal early development followed by the sudden onset in infancy of poor feeding, dysphagia, truncal (followed by global) hypotonia, motor regression, abnormal movements (i.e. severe dystonia of limbs, choreoathetosis, facial dyskinesias) and reduced tendon reflexes. The disease course is severe but nonprogressive.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Increased circulating lactate concentration · Very frequent (99-80%)

Abnormally increased level of blood lactate (2-hydroxypropanoic acid). Lactate is produced from pyruvate by lactate dehydrogenase during normal metabolism. The terms lactate and lactic acid are often used interchangeably but lactate (the component measured in blood) is strictly a weak base whereas lactic acid is the corresponding acid. Lactic acidosis is often used clinically to describe elevated lactate but should be reserved for cases where there is a corresponding acidosis (pH below 7.35).

Mitochondrial respiratory chain defects · Very frequent (99-80%)

Abnormal corpus striatum morphology · Frequent (79-30%)

Abnormality of the striatum, which is the largest nucleus of the basal ganglia, comprising the caudate, putamen and ventral striatum, including the nucleus accumbens.

Axial hypotonia · Frequent (79-30%)

Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk.

Choreoathetosis · Frequent (79-30%)

Involuntary movements characterized by both athetosis (inability to sustain muscles in a fixed position) and chorea (widespread jerky arrhythmic movements).

Delayed myelination · Frequent (79-30%)

Delayed myelination.

Generalized hypotonia · Frequent (79-30%)

Generalized muscular hypotonia (abnormally low muscle tone).

Increased CSF lactate · Frequent (79-30%)

Increased concentration of lactate in the cerebrospinal fluid.

Limb dystonia · Frequent (79-30%)

A type of dystonia (abnormally increased muscular tone causing fixed abnormal postures) that affects muscles of the limbs.

Muscle weakness · Frequent (79-30%)

Reduced strength of muscles.

Nystagmus · Frequent (79-30%)

Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.

Poor head control · Frequent (79-30%)

Difficulty to maintain correct position of the head while standing or sitting. Infant head lag is observed when the head seems to flop around or lags posteriorly behind the trunk. Several articles have maintained that head lag should be absent by age 3 to 4 months.

Sensorineural hearing impairment · Frequent (79-30%)

A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.

Profound static encephalopathy · Frequent (79-30%)

Other findings in the same source

From: Orphanet

Additional reported features include Abnormal basal ganglia morphology (Occasional (29-5%)); Abnormal corpus callosum morphology (Occasional (29-5%)); Abnormality of eye movement (Occasional (29-5%)); Absent speech (Occasional (29-5%)); Decreased nerve conduction velocity (Occasional (29-5%)); Developmental cataract (Occasional (29-5%)); Elevated CSF neopterin level (Occasional (29-5%)); Failure to thrive (Occasional (29-5%)); Feeding difficulties (Occasional (29-5%)); Gastrostomy tube feeding in infancy (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Infancy

Inheritance in the source

From: Orphanet

Autosomal recessive

Frequency and the population described

From: Orphanet

Reported case(s): 2.0; Worldwide. This is a published case count, not prevalence. Point prevalence: <1 / 1 000 000; Worldwide; Class only.

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 Combined oxidative phosphorylation defect type 13 is Metabolic Medicine, with a metabolic specialist / clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with metabolic specialist / 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.

• Is a biochemical or molecular result needed to clarify the diagnosis?
• Does this condition require an individual plan for illness or reduced food intake?
• Should nutrition advice come from a specialist metabolic dietitian?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Combined oxidative phosphorylation defect type 13. 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.