Genetic predisposition Flashcards
(17 cards)
What does this explanation state?
Those with ASB have a genetic predisposition to the disorder
What are the two types of studies that are used?
Family and twin studies
How much genes do first degree relatives share?
50% of there genes
How much genes do second degree relatives share?
25% of there genes
What did Szatmari find?
The sibling risk was calculated at 2.2% of developing it, Non sibling risk is 0.11%, 20x greater risk if sibling has it
What did Ritvo et al find?
Concordance rate 96% for MZ and 23% for DZ
What did Bailey et al find?
Concordance rate for MZ 60% and DZ 0%, widened definition for ASB, 92% for MZ and 10% for DZ
How can the studies be criticised?
Studies before 2013 are based off the old criteria of ASB
Lacks temporal validity- may not be correct based on current criteria
Consistency issues- disagreement and agreement on concordance rates
What is simplex ASB?
When only 1 member has ASB that is known
What is multiplex ASB?
When more than one member has known ASB
What is thought for simplex and multiplex families?
Genetic vulnerability differs
How is ASB likely to be caused in multiplex families?
Genetic variation that is inherited
How is ASB likely to be caused in simplex families?
New genetic mutations occur when sequences of DNA are duplicated as an ovum is fertilised by the sperm, mutation is replicated during division which affects multiple genes (Copy number variation)
How much does copy number variation account for in ASB?
10%
Why is there a difference between family and twins studies?
Simplex caused at fertilisation so will happen to both MZ twins
multiplex is inherited- concordance could be lower in DZ and siblings as they can inherit difference genes
What is a strength of the explanation?
Reductionist, researcher can focus on one component of ASB, however it over simplifies the explanation, other potential influences are ignored
What is a weakness of the explanation?
Out of 26,000 cases non have family history
There are additional risk factors (Wendy Chung), problems may occur in early pregnancy such as infections that are thought to be risk factors
