Huntington’s Chorea

• Huntington’s disease (also called Huntington’s chorea) is an autosomal dominant genetic condition that causes progressive neurological dysfunction.
• Huntington’s disease is a trinucleotide repeat disorder involving a genetic mutation in the HTT gene on chromosome 4, which codes for the huntingtin (HTT) protein.
• Symptoms of Huntington’s disease typically begin aged 30-50.
• Trinucleotide repeats refer to repetitions of a sequence of three nucleotides (e.g., CAGCAGCAGCAGCAG).
• Examples of trinucleotide repeat disorders include Fragile X syndrome, Spinocerebellar ataxia, Myotonic dystrophy, Friedrich ataxia, and Anticipation.
• Huntington’s chorea displays something called genetic anticipation.
• Anticipation is a feature of trinucleotide repeat disorders, where successive generations have more repeats in the gene, resulting in earlier age of onset and increased severity of disease.
• The child of someone with Huntington’s chorea has a 50% chance of inheriting the faulty gene (it is autosomal dominant) and needs to be 18 before they can decide whether to get tested.
• There are currently no treatment options for slowing or stopping the progression of Huntington’s chorea.
• Diagnosis of Huntington’s chorea is made by genetic testing via a specialist genetic centre and involves pre and post-test counselling.
• Huntington’s chorea typically begins with cognitive, psychiatric or mood problems, followed by the development of movement disorders: Chorea (involuntary, random, irregular and abnormal body movements), Dystonia (abnormal muscle tone, leading to abnormal postures), Rigidity (increased resistance to the passive movement of a joint), Eye movement disorders, Dysarthria (speech difficulties), Dysphagia (swallowing difficulties).
• Death from Huntington’s chorea is often due to aspiration pneumonia or suicide.
• Management of Huntington’s chorea involves supporting the person and their family: Breaking bad news effectively and supportively, Genetic counselling regarding relatives, pregnancy and children, Multidisciplinary team (MDT) input to support and maintain their quality of life, Physiotherapy to improve mobility, maintain joint function and prevent contractures, Speech and language therapy where there are speech and swallowing difficulties.
• Huntington’s chorea is a progressive condition with a life expectancy of around 10-20 years after the onset of symptoms.
• Huntington’s chorea presents with an insidious, progressive worsening of symptoms.
• Tetrabenazine may be used for chorea symptoms, Antidepressants (e.g., SSRIs) for depression, Advanced directives to document their wishes as the disease progresses, End-of-life care.
• As the disease progresses, patients become more frail and susceptible to illness such as infections, weight loss, falls and pressure ulcers.