Costeff syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Costeff syndrome is an inherited condition characterized by vision loss, delayed development, and movement problems. Vision loss is primarily caused by degeneration (atrophy) of the optic nerves, which carry information from the eyes to the brain. This optic nerve atrophy often begins in infancy or early childhood and results in vision impairment that worsens over time. Some affected individuals have rapid and involuntary eye movements (nystagmus) or eyes that do not look in the same direction (strabismus).

Development of motor skills, such as walking, is often delayed in people with Costeff syndrome. Affected individuals may also have speech difficulties (dysarthria). While some people with Costeff syndrome have mild to moderate intellectual disability, many have normal intelligence.

Movement problems in people with Costeff syndrome develop in late childhood and include muscle stiffness (spasticity), impaired muscle coordination (ataxia), and involuntary jerking movements (choreiform movements). As a result of these movement difficulties, individuals with Costeff syndrome may require wheelchair assistance.

Costeff syndrome is associated with increased levels of a substance called 3-methylglutaconic acid in the urine (3-methylglutaconic aciduria). The amount of this substance does not appear to influence the signs and symptoms of the condition. Costeff syndrome is one of a group of metabolic disorders that can be diagnosed by the presence of 3-methylglutaconic aciduria. People with Costeff syndrome also have high levels of another acid called 3-methylglutaric acid in their urine.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in a gene called OPA3 cause Costeff syndrome. The OPA3 gene provides instructions for making a protein whose exact function is unknown. The OPA3 protein is found in structures called mitochondria, which are the energy-producing centers of cells. It is thought to play a role in the organization of the shape and structure of mitochondria and in controlled cell death (apoptosis).

OPA3 gene mutations that result in Costeff syndrome lead to a loss of OPA3 protein function. Cells without any functional OPA3 protein have abnormally shaped mitochondria. These cells likely have reduced energy production and die prematurely, decreasing energy availability in the body's tissues. Cells in the eyes and brain have high energy demands, and it is likely that they are particularly vulnerable to cell death due to dysfunctional mitochondria and reduced energy production.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Costeff syndrome affects an estimated 1 in 10,000 individuals in the Iraqi Jewish population, in which at least 40 cases have been described. Outside this population, only a few affected individuals have been identified.

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.

3-Methylglutaconic aciduria · Very frequent (99-80%)

An increased amount of 3-methylglutaconic acid in the urine.

Choreoathetosis · Very frequent (99-80%)

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

Visual impairment · Very frequent (99-80%)

Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.

Ataxia · Frequent (79-30%)

Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).

Dysarthria · Frequent (79-30%)

Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.

Intellectual disability · Frequent (79-30%)

The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence.

Nystagmus · Frequent (79-30%)

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

Spastic paraparesis · Frequent (79-30%)

Partial loss of the ability to move the lower limbs accompanied by spasticity of the lower limbs.

Other findings in the same source

From: Orphanet

Additional reported features include Gait disturbance (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Costeff syndrome 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 Costeff 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.