genetic predisposition of adult onset disease Flashcards
what is penetrance?
this is a measurement of how many people with a particular genotype display that phenotype.
For example - Huntingtons disease has a 100% penetrance (meaning anyone with the gene will inevitable develop the disease).
what is predictive testing?
Testing someone currently well to predict their future.
what is carrier testing?
testing done to determine if someone is a carrier of an autosomal recessive gene.
what is cascade screening?
screening of family members to identify if they are at risk of a hereditary disease.
how can genetics be altered?
4 methods
- Single gene: (x-linked), autosomal dominant, autosomal recessive.
- chromosomal: trisomy
- Mitochondrial
- Multifactorial
how can genetics be altered?
4 methods
- Single gene: (x-linked), autosomal dominant, autosomal recessive.
- chromosomal: trisomy
- Mitochondrial
- Multifactorial
what are characteristics of an entirely genetic disease?
- unifactorial
- rare
- high recurrence rate for family members
what are characteristics of a more environmental disease?
- common
- genetic complex
- multifactorial
- low recurrence rate
what must genetic test information be able to do?
- benefit the patient
- allow for prevention or treatment
what is x linked inheritance?
when the gene causing the disease is located on the X chromosome.
what is x linked inheritance?
when the gene causing the disease is located on the X chromosome.
what is a non-penetrant individual?
when someone has the genotype for a disease but it fails to cause disease.
Eg - women with BRCA1 who never develop breast cancer.
What is ALS?
amyotrophic lateral sclerosis (motor neurone disease)
how much motor neurone disease is genetic?
5-10%, the rest is sporadic.
There is no PARTICULAR gene which causes ALS.
what type of autosomal gene can ALS be?
The gene causing motor neurone disease can be either autosomal dominant OR recessive.
what type of autosomal gene can ALS be?
The gene causing motor neurone disease can be either autosomal dominant OR recessive.
what is the average onset of MND?
55yrs.
But YOUNGER in familial forms.
what are the most common types of motor neurone disease?
amyotrophic lateral sclerosis
progressive bulbar palsy
what is the most common cause of death in MND?
respiratory failute
what enzyme is affected in ALS?
SOD
superoxide dismutase
(20% in familial cases, only 2% in non familial cases).
what is the role of SOD?
This is an enzyme which breaks down harmful oxygen molecules (free radicals) preventing tissue damage.
what is the treatment for ALS?
No cure or good treatment.
what is Huntingtons disease?
An adult onset autosomal dominant disease.
what are the clinical features of Huntingtons disease?
Chorea athetosis (slow writhing movements) myoclonis rigidity poor planning un classical dementia irritable depressed anxious loss of empathy paranoia psychosis disinhibition Wide stance
