Familial encephalopathy with neuroserpin inclusion bodies

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Familial encephalopathy with neuroserpin inclusion bodies (FENIB) is a disorder that causes progressive dysfunction of the brain (encephalopathy). This condition is characterized by a loss of intellectual functioning (dementia) and seizures.

The first signs of intellectual impairment in individuals with FENIB may be problems with attention and concentration. Affected individuals may have trouble regulating their thoughts or speech. As the condition progresses, personality changes develop, and judgment, insight, and memory become impaired. Affected individuals lose the ability to perform the activities of daily living, and most eventually require comprehensive care.

People with FENIB have seizures that involve a sudden, involuntary muscle jerking or twitching (myoclonus). Many also experience at least one other form of seizure, typically generalized seizures that involve a loss of consciousness, muscle rigidity, and convulsions. In rare cases, people with FENIB have prolonged episodes of seizure activity that last several minutes (status epilepticus). In most people with FENIB, anti-seizure medications are not effective. Many people with FENIB have other types of involuntary movement (dyskinesia).

The signs and symptoms of FENIB can appear at any age, and they vary in severity. In severe cases, dementia can appear in childhood or adolescence and is often the first sign of the condition. Less severe cases are characterized by a progressive decline in intellectual functioning that begins in mid- to late adulthood.

People with FENIB have a shortened life expectancy. The earlier the signs and symptoms appear, the greater the impact on life expectancy. Causes of death in people with FENIB include status epilepticus and pneumonia.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

FENIB is caused by variants (also called mutations) in the SERPINI1 gene. This gene provides instructions for making a protein called neuroserpin, which is found primarily in nerve cells (neurons). This protein helps neurons divide and mature so they can take on specific functions (differentiation). The connections between neurons (synapses) also need neuroserpin to function properly, which suggests that this protein may be important for learning and memory.

SERPINI1 gene variants can cause cells to produce an abnormally shaped, unstable form of neuroserpin. Within neurons, these altered neuroserpin proteins attach to one another and form chains (neuroserpin polymers) that clump together to form neuroserpin inclusion bodies. These inclusion bodies disrupt the normal functioning of neurons and ultimately lead to cell death. Additionally, the formation of neruoserpin polymers likely increases the release of calcium ions into the cell. This can lead to certain neurons becoming more active than usual, which may trigger the abnormal brain activity that is associated with seizures in people with FENIB.

The encephalopathy and dementia in people with FENIB occur as neuroserpin inclusion bodies accumulate in the brain, causing the gradual loss of neurons. Larger numbers of inclusion bodies cause more severity of the neurological problems. People with severe FENIB tend to have more widespread neuron loss than those with milder cases of FENIB.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

FENIB is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In some cases, this condition is familial, which means an affected person inherits the variant from one affected parent. Other cases are sporadic and result from a new (de novo) variant in the gene that occurs during the formation of reproductive cells (eggs or sperm) in an affected individual's parent or during early embryonic development. These affected individuals typically have no history of the disorder in their family.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

FENIB appears to be very rare. The condition was first described in 1999 and at least 13 affected individuals have been reported worldwide.

Which doctor should you see?

The suggested department for discussing Familial encephalopathy with neuroserpin inclusion bodies is Neurology, with a neurologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

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.

• Which nervous-system findings help explain the symptoms?
• Would an assessment of walking, communication or daily function be helpful?
• Are rehabilitation or other specialist services relevant?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Familial encephalopathy with neuroserpin inclusion bodies. 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.