From the Guidelines
Yes, a patient can have Huntington's disease without a family history, as the disease can result from new genetic mutations or other factors not related to familial inheritance. This is supported by the fact that Huntington's disease is a hereditary, autosomal dominant fatal neurodegenerative disorder with complete penetrance, but the genetic basis of the disease is an abnormally increased number of CAG repeats in the huntingtin gene, which can occur spontaneously 1. The incidence of Huntington's disease is approximately 10/100,000, with an average age of onset between 35 to 45 years, and symptom progression until death within 15 to 20 years of onset. Key points to consider include:
- The disease is caused by an expansion of CAG repeats in the HTT gene on chromosome 4, and this mutation can occur spontaneously.
- Genetic testing can confirm the diagnosis by measuring the number of CAG repeats, with more than 38 repeats being diagnostic 1.
- Patients with suspected Huntington's disease should undergo genetic counseling and testing to exclude or confirm the disease, given that imaging may be normal early on in the disease course 1.
- If someone develops Huntington's disease without a family history, their children will still have a 50% chance of inheriting the mutation.
- Anyone experiencing symptoms like involuntary movements, cognitive decline, or psychiatric issues should seek medical evaluation regardless of family history.
From the Research
Huntington's Disease Without Family History
- Huntington's disease (HD) is an inherited neurodegenerative disorder, but it is possible for a patient to have HD without a known family history 2.
- A study found that 4.81% of mutation-positive subjects had a negative family history, suggesting that some cases of HD may not be linked to a known family history 2.
- The absence of a family history does not rule out the possibility of HD, as the disease can be caused by a de novo mutation or other genetic factors 3, 4.
- Diagnosis of HD is typically confirmed through genetic testing, which identifies an increased CAG repeat length in the huntingtin gene 3, 5.
- Patients with HD without a family history may still exhibit the characteristic symptoms of the disease, including cognitive, motor, and psychiatric disturbances 6, 4.