3- Genetic Basis of Schizophrenia

Question 1

Who interviewed relatives of people with schizophrenia?

Answer 1

Kendler

Question 2

What did Kendler find about the genetic link in schizophrenia?

Answer 2

Chances of developing schizophrenia are 13 times more likely if a member of immediate family is affected

Question 3

How do data from family and twin studies support of polygenic model of inheritance?

Answer 3

Show that risk of schizophrenia increases with increased relatedness with an affected individual

Question 4

How do twin studies show a genetic basis for schizophrenia?

Answer 4

MZ twins higher concordance rate than DZ twins

Question 5

How much is the schizophrenia heritability estimated to be from twin studies?

Answer 5

At 81%

Question 6

How much is the shared environment estimate from twin studies?

Answer 6

11%

Question 7

What are the 3 genetic explanations of schizophrenia?

Answer 7

1. Highly polygenic
2. Pleiotropic
3. Convergence of genetic findings suggest particular biological processes

Question 8

2 explanations of schizophrenia being highly polygenic

Answer 8

1. Lots of genes contribute
2. Different genes contribute

Question 9

2 explanations of schizophrenia being pleiotropic

Answer 9

1. Same genes contributing to several different phenotypes
2. Not necessarily specific factors to schizophrenia

Question 10

What is schizophrenia associated with?

Answer 10

Reduced fecundity

Question 11

What is the hypothesis about why common high risk schizophrenia genes aren’t found much?

Answer 11

Because they have been selected out across generations

Question 12

What 2 aspects of schizophrenia genes might natural selection explain?

Answer 12

1. Rare
2. Small effect size

Question 13

What was shown by the Psychiatric Genomics Consortium?

Answer 13

Schizophrenia is polygenic

Question 14

What do family and twin data suggest schizophrenia is caused by in the Psychiatric Genomics Consortium?

Answer 14

Caused by many genetic variants of small effects

Question 15

What is the schizophrenia polygenic risk score?

Answer 15

Sum of risk alleles identified as associated with schizophrenia

Question 16

When is the polygenic risk score used?

Answer 16

As a predictor in a regression

Question 17

What does the polygenic risk score offer?

Answer 17

An indication of genetic overlap between schizophrenia and other measures

Question 18

What did Genovese et al find?

Answer 18

Gene-disruptive and protein-damaging very rare genetic variants are commonly found in those with schizophrenia

Question 19

Where are ultra-rare protein-altering genetic variants associated with schizophrenia found?

Answer 19

Concentrated in brain-expressed genes, specifically in neuron-specific genes and particularly involving synaptic genes