Huntington Disease
Progressive; autosomal dominant; usually adult onset; with movement disorder (usually chorea), personality disorder, dementia.
Pathology: generalized brain atrophy; striatum (caudate nucleus, putamen) most affected.
Biochemistry: loss of striatal and nigral neurons synthesizing γ-aminobutyric acid (GABA); possible excitotoxicity.
Prevalence: 4 to 8/100,000 in United States, Europe; 10 times less prevalent in Japan.
Genetics
Expansion of CAG trinucleotide repeat in HD gene (chromosome 4). Number of repeats inversely correlated with age at symptom onset. Expansion unstable in sperm only: paternal transmission associated with increased number of repeats, younger onset age in offspring. Neuronal accumulation of gene product (huntingtin).
Signs and Symptoms
Symptom onset usually age 35 to 40 (range: 5 to 70). Movement disorder, personality disorder, mental deterioration together or in any order.
Typical course: clumsiness, drop objects, fidgetiness, irritability, slovenliness, neglect duties, then frank chorea, dementia. Duration variables, around 15 to 20 years; more rapid with earlier age onset.Related posts:
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