Neurológia pre prax 3/2012
Juvenile form of Huntington's disease
Huntington's disease (HD) is an autosomal dominant hereditary neurodegenerative disease with an incidence of approximately 1:10-15000. The mutation involves an expansion of CAG triplets in the first exon. An individual develops HD when the number of triplets is 40 or more. A typical age of onset of initial symptoms in classic, adult-onset HD is between 35 and 50 years of age. Much more rarely (approximately 5% of all cases), HD develops in child or adolescent age (juvenile form of HD /JHD/, arbitrarily defined as a disease with the onset of clinical manifestations by 20 years of age). This form of disease usually occurs when the number of CAG triplet repeats exceeds 60. Intellectual impairment often occurs first. A typical initial manifestation of JHD is failure to cope with academic demands, particularly due to a combination of cognitive disorder with motor slowing, discoordination of movement and voluntary movement disorder. Also typical are conduct disorders: most commonly temper tantrums, aggressiveness, antisocial behaviour and obsessive-compulsive features. JHD is most typically characterized by hypokinesis, rigidity, and dystonia, accompanied by rapidly progressive stability and gait disturbances. Chorea is usually absent. A relatively early occurrence is dysarthria, which may progress to mutism in the later stages, and dysphagia. JHD is sometimes referred to as primary Westphal variant HD. Another relatively common manifestation in JHD is epileptic seizures. Cachexia constantly occurs as early as the middle stages of the disease. To date, there have been no standards or uniform recommendations for therapeutic management in JHD. There are no pharmacological studies investigating symptomatic effects of drugs that would meet the requirements of evidence-based medicine; everything is off-label treatment. The article describes the therapeutic options used in individual manifestations of JHD.
Keywords: Huntington's disease, juvenile form, Westphal variant, CAG triplet.
