Lissencephaly with cerebellar hypoplasia

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Lissencephaly with cerebellar hypoplasia (LCH) affects brain development, resulting in the brain having a smooth appearance (lissencephaly) instead of its normal folds and grooves. In addition, the part of the brain that coordinates movement is unusually small and underdeveloped (cerebellar hypoplasia). Other parts of the brain are also often underdeveloped in LCH, including the hippocampus, which plays a role in learning and memory, and the part of the brain that is connected to the spinal cord (the brainstem).

Individuals with LCH have moderate to severe intellectual disability and delayed development. They have few or no communication skills, extremely poor muscle tone (hypotonia), problems with coordination and balance (ataxia), and difficulty sitting or standing without support. Most affected children experience recurrent seizures (epilepsy) that begin within the first months of life. Some affected individuals have nearsightedness (myopia), involuntary eye movements (nystagmus), or puffiness or swelling caused by a buildup of fluids in the body's tissues (lymphedema).

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

LCH can be caused by mutations in the RELN or TUBA1A gene. The RELN gene provides instructions for making a protein called reelin. In the developing brain, reelin turns on (activates) a signaling pathway that triggers nerve cells (neurons) to migrate to their proper locations. The protein produced from the TUBA1A gene is also involved in neuronal migration as a component of cell structures called microtubules. Microtubules are rigid, hollow fibers that make up the cell's structural framework (the cytoskeleton). Microtubules form scaffolding within the cell that elongates in a specific direction, altering the cytoskeleton and moving neurons.

Mutations in either the RELN or TUBA1A gene impair the normal migration of neurons during fetal development. As a result, neurons are disorganized, the normal folds and grooves of the brain do not form, and brain structures do not develop properly. This impairment of brain development leads to the neurological problems characteristic of LCH.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

When LCH is caused by mutations in the RELN gene, the 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.

When LCH is caused by mutations in the TUBA1A gene, the 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 of these cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

LCH is a rare condition, although its prevalence is unknown.

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.

Severe intellectual disability

Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34.

Intellectual disability

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.

Cerebellar hypoplasia

Cerebellar hypoplasia is a descriptive term implying a cerebellum with a reduced volume, but a normal shape and is stable over time.

Lissencephaly

A spectrum of malformations of cortical development caused by insufficient neuronal migration that subsumes the terms agyria, pachygyria and subcortical band heterotopia. See also neuropathological definitions for 2-, 3-, and 4-layered lissencephaly.

Lymphedema

Localized fluid retention and tissue swelling caused by a compromised lymphatic system.

Which doctor should you see?

The suggested department for discussing Lissencephaly with cerebellar hypoplasia 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 Lissencephaly with cerebellar hypoplasia. 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.