Spinocerebellar ataxia 34

Alternate names

SCA34; Giroux Barbeau Syndrome; Erythrokeratodermia - ataxia; Erythrokeratodermia with ataxia

Definition

An autosomal dominant cerebellar ataxia type I that is characterized by papulosquamous, ichthyosiform plaques on the limbs appearing shortly after birth and later manifestations including progressive ataxia, dysarthria, nystagmus and decreased reflexes.

Epidemiology

To date the disorder has been reported in 45 patients including 4 asymptomatic carriers, from one French-Canadian family and three Japanese families.

Cause

The disorder is due to a mutation in the ELOVL4 gene (6q14).

Inheritance

• The disorder is inherited in an autosomal dominant manner and genetic counseling is possible.
• Genetic counseling should be proposed to individuals having the disease-causing mutation informing them that there is 50% risk of passing the mutation to offspring.

Signs and symptoms

• Disease onset occurs from shortly after birth to adolescence with the appearance of papulosquamous, ichthyosiform plaques on the limbs, which are often only present in the winter.
• After the age of 25 years they tend to disappear completely.
• Progressive ataxia, dysarthria, decreased reflexes, and nystagmus are further clinical signs of the disease that occur after the onset of skin manifestations, generally from the third to fifth decade of life.
• Patients occasionally present with autonomic dysfunction and pyramidal signs.
• Cerebellar and pontine atrophy is visible with magnetic resonance imaging (MRI) in individuals who develop cerebellar ataxia.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Dry skin
• Dysarthria(Difficulty articulating speech)
• Dysdiadochokinesis(Difficulty performing quick and alternating movements)
• Gait disturbance(Abnormal gait)
• Hypohidrosis(Decreased ability to sweat)
• Hyporeflexia(Decreased reflex response)
• Macule(Flat, discolored area of skin)
• Nystagmus(Involuntary, rapid, rhythmic eye movements)
• Papule
• Progressive cerebellar ataxia
• Urticaria(Hives)

5%-29% of people have these symptoms

• Abnormality of the musculature(Muscular abnormality)
• Facial asymmetry(Asymmetry of face)
• Fasciculations(Muscle twitch)
• Intention tremor
• Spasticity(Involuntary muscle stiffness, contraction, or spasm)
• Strabismus(Cross-eyed)

1%-4% of people have these symptoms

• Peripheral axonal neuropathy

Diagnosis

• Diagnosis is based on characteristic clinical findings (skin lesions occurring shortly after birth and adult-onset slowly progressive cerebellar ataxia), and on the molecular genetic testing.
• Mutations in the ELOVL4 gene confirms diagnosis of SCA34.
• Magnetic resonance imaging usually shows marked atrophy of the cerebellum and pontine which is sometimes accompanied by Hot Cross Bun sign that is common in cerebellar type of multiple system atrophy.

Antenatal diagnosis Antenatal diagnosis is possible in families with a known ELOVL4 mutation.

Treatment

• Treatment is only supportive.
• Physical activity should be maintained as much as possible with the help of prosthetic devices.
• Motorized chairs/scooters are eventually necessary.
• Speech therapy and communication devices should be offered to those with severe dysarthria.

Prognosis

Disease progression is slow; the patients require cane or walker in their late 60s, and wheelchair in their 70s.

NIH genetic and rare disease info

• NIH info on Spinocerebellar ataxia 34

Spinocerebellar ataxia 34 is a rare disease.

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