Joubert Anomaly and Syndrome Overview

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Questions and Answers

What genetic inheritance pattern is associated with Joubert anomaly?

  • X-linked recessive
  • Autosomal dominant
  • Autosomal recessive (correct)
  • Mitochondrial inheritance

Which of the following symptoms is commonly observed in patients with Joubert syndrome?

  • Visual agnosia
  • Speech fluency
  • Oculomotor apraxia (correct)
  • Tinnitus

Which chromosome mutation is linked to some cases of Joubert syndrome?

  • Chromosome 15q12
  • Chromosome 7p14
  • Chromosome 9q34.3 (correct)
  • Chromosome 2q35

What is the approximate prevalence of Joubert syndrome?

<p>1 in 100,000 (A)</p> Signup and view all the answers

What is a significant feature of the neuromotor development in individuals with Joubert syndrome?

<p>Persistent neuromotor developmental delay (A)</p> Signup and view all the answers

What type of imaging typically demonstrates abnormalities in patients with Joubert syndrome?

<p>Magnetic resonance imaging (MRI) (C)</p> Signup and view all the answers

Which of the following represents an increased risk associated with Joubert syndrome during medical treatment?

<p>Sensitivity to agents causing respiratory depression (C)</p> Signup and view all the answers

What cognitive impairment range is typically observed in individuals with Joubert syndrome?

<p>IQ between 30 and 80 (A)</p> Signup and view all the answers

Flashcards

Joubert Anomaly

An autosomal recessive disorder characterized by a variable degree of cerebellar vermis agenesis. It often presents with ataxia, dysmorphic facies, global developmental delay, hypotonia, rapid breathing, and oculomotor apraxia.

Joubert Syndrome and Related Disorders (JSRD)

A condition related to Joubert Anomaly, but also includes anomalies in the kidneys, liver, and/or eyes.

Oculomotor Apraxia

A common feature of Joubert Syndrome, characterized by difficulty controlling eye movements.

Cerebellar Vermal Agenesis

The presence of abnormally small or malformed cerebellar vermis.

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Ataxia

The condition of lacking coordination and balance.

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Nystagmus

A specific type of eye movement that is abnormal in Joubert Syndrome. It involves rapid, involuntary movements of the eyes.

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Ciliopathies

Disorders that affect the primary cilium and basal body of cells. Joubert Syndrome is an example of a ciliopathy.

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Heterotopia

The presence of abnormal brain tissue in a location where it should not be.

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Study Notes

Joubert Anomaly (and Joubert Syndrome)

  • Joubert anomaly, also known as vermian aplasia or molar tooth midbrain-hindbrain malformation, is an autosomal recessive disorder.
  • Characterized by variable cerebellar vermal agenesis.
  • When associated with kidney, liver, or eye anomalies, it's called Joubert syndrome or related disorders (JSRD).
  • Prevalence is approximately 1 in 100,000.

Clinical Presentation

  • Affected individuals often present with ataxia.
  • Dysmorphic facial features are common.
  • Global developmental delay is typical.
  • Hypotonia (low muscle tone) is frequently observed.
  • Rapid breathing (tachypnea) may occur.
  • Oculomotor apraxia (difficulty with eye movements) is present.
  • Cognitive impairment ranges significantly, from IQ 30 to 80, though assessment is challenging due to speech and motor deficits.
  • Nystagmus (involuntary eye movements) and impaired smooth pursuit eye movements are common.

Genetic Basis

  • Joubert syndrome is a genetically heterogeneous condition.
  • Some cases involve mutations on chromosome 9q34.
  • Many cases do not involve this chromosome.
  • At least ten genes related to subcellular organelles (including primary cilia and basal bodies) are implicated.
  • This classification places Joubert syndrome within the broader category of ciliopathies.

Imaging Findings

  • Cross-sectional axial imaging reveals cerebellar dysplasia and heterotopia of cerebellar nuclei.
  • Minor lateral ventriculomegaly (6-20%) and corpus callosal dysgenesis (6-10%) are sometimes present.

Prognosis and Management

  • Long-term outcome data for children with Joubert syndrome is limited.
  • Persistent neuromotor developmental delay is a common feature in surviving individuals.
  • Patients with retinal dysplasia have a potentially poorer prognosis.
  • Extreme caution is advised when administering agents that cause respiratory depression, as affected individuals are highly sensitive to these effects.
  • Genetic counselling is essential due to the autosomal recessive nature of the condition.

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