DLG4-related synaptopathy

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

DLG4-related synaptopathy is a condition that affects neurological development. This condition is characterized by delayed development and mild to moderate intellectual disabilities that typically becomes evident before age 2. Over time, many individuals with DLG4-related synaptopathy lose skills that they have learned, such as speech or motor skills. About 20 percent of people with this condition cannot speak. Affected individuals often have neurodevelopmental disorders, such as autism spectrum disorder or attention-deficit/hyperactivity disorder. About half of individuals with this condition have recurrent seizures (epilepsy) that typically begin in childhood. Brain changes can also occur. These include brain tissue loss (atrophy) and abnormalities of the tissue connecting the left and right halves of the brain (corpus callosum) or the hippocampus, which is a region of the brain that is involved in learning and memory.

Individuals with DLG4-related synaptopathy can also have weak muscle tone (hyptonia), loose joints (joint laxity), or a spine that curves to the side (scoliosis). Movement problems, including impaired muscle coordination (ataxia), involuntary muscle coordination (dystonia), or rhythmic shaking (tremor) are common in people with this condition. Other problems can include migraine, sleep problems, or anxiety. Some people with DLG4-related synaptopathy have a distinctive body type that includes a long face, slim body, and long fingers.

Less commonly, DLG4-related synaptopathy can affect a person's vision. Affected individuals can have eyes that do not point in the same direction (strabismus), farsightedness (hyperopia), or involuntary movements of the eyes (nystagmus). Some affected individuals have blindness because the area of the brain responsible for processing vision is impaired.

DLG4-related synaptopathy can also cause gastrointestinal difficulties that make it difficult to eat. These can include a backflow of stomach acids into the esophagus (gastroesophageal reflux disease or GERD).

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

The DLG4 gene provides instructions for making a protein that plays a role in nerve cells (neurons) in the brain. The DLG4 protein is found at synapses, which are the connections between neurons where cell-to-cell communication occurs. The DLG4 protein plays roles in synaptic signaling, development, survival, and function. In particular, this protein interacts with other proteins to regulate a process called synaptic plasticity, which allows synapses to change and adapt over time in response to experience. Synaptic plasticity is critical for learning and memory.

Variants (also called mutations) in the DLG4 gene cause DLG4-related synaptopathy. Most of these variants impair the normal function of the DLG4 protein by decreasing its ability to interact with the other proteins involved in synaptic plasticity or decreasing its ability to help synapses send signals. Other variants prevent the production of any normal DLG4 protein. The signs and symptoms of DLG4-related synaptopathy are likely caused by the reduced ability of synapses to change and adapt during important periods of brain development. Movement problems seen in people with DLG4-related synaptopathy may because caused by signaling changes at certain synapses. .cf0{font-family:Segoe UI;font-size:9pt;}In addition, changes that impact synapse development and activity may cause seizures in people with this condition.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases of this condition result from new (de novo) variants in the gene that occur during the formation of reproductive cells (eggs or sperm) in an affected individual's parent or in early embryonic development. These affected individuals have no history of the disorder in their family.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

DLG4-related synaptopathy is a rare disorder, although its exact prevalence is unknown. This condition has been reported in at least 100 people.

Which doctor should you see?

The suggested department for discussing DLG4-related synaptopathy 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 DLG4-related synaptopathy. 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.