8: Psychiatric genetics Flashcards
What is the mode of inheritance of Huntington’s disease?
Autosomal dominant
What are the chances of a child inheriting an autosomal dominant condition?
50%
What is anticipation?
As a mutated gene is passed down through generations, the presentation of the disease gets worse
e.g Huntington’s (inherited CAG repeats)
What is the genetic cause of Huntington’s disease?
Huntingtin gene mutates
CAG triplet repeats code for glutamine
You should have < 38, 32-38 may cause you to pass it on by anticipation, >38 means a definite onset of HD
What is the primary determinant of HD onset?
Number of CAG repeats (>38)
The more CAG repeats you have (over 38), the ___ your onset of Huntington’s disease.
earlier
What is the course and prognosis of Huntingtons disease?
Unremitting, progressive course
Untreatable (only symptomatic), eventual death
What is the usual mode of inheritance of dementia?
Multifactorial
What features of the history indicate a patient has a familial form of a disease?
Unusual clinical features
More family members affected
Family members affected at a young age
What is your lifetime risk of developing Alzheimer’s disease?
10%
If you have a first degree relative with Alzheimer’s disease, what is your risk of developing the condition?
25%
What is the prevalence of bipolar type 1?
1%
What is the mode of inheritance of bipolar disorder?
Probably multifactorial
