Psychosis Heritability and Risk Factors

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Questions and Answers

What does a polygenic risk score (PRS) measure?

The likelihood of developing a specific type of cancer

The environmental factors influencing mental health

A person's genetic predisposition to developing certain conditions (correct)

The effectiveness of a medication based on genetic makeup

Which of the following is considered a good biomarker?

Invasive and expensive to measure

Only affects individuals in specific age groups

Commonly available but unreliable

Strongly associated with the disease and heritable (correct)

How do endophenotypes contribute to understanding diseases like schizophrenia?

They improve disease classification and treatment personalization (correct)

They replace the need for genetic testing

They solely focus on environmental factors

They predict the exact outcome for all patients

What is the role of genetic counseling in mental health?

To inform about the management of genetic disorders Signup and view all the answers

What percentage of variance in risk does the sample PRS indicate for schizophrenia?

9% Signup and view all the answers

Which genetic component has been linked with both schizophrenia and bipolar disorder?

Single nucleotide polymorphisms (SNPs) Signup and view all the answers

What percentage of psychosis is considered to be heritable?

80% Signup and view all the answers

What does pharmaco-genetics aim to achieve?

To personalize treatment based on genetic tests Signup and view all the answers

Which of the following is a significant environmental factor associated with an increased risk of psychosis?

Cannabis use Signup and view all the answers

Which indicator is associated with poorer verbal and spatial learning in carriers of schizophrenia-associated CNVs?

P300 wave changes on EEG Signup and view all the answers

Which genetic variations are known as strong risk factors contributing to schizophrenia?

Copy Number Variants Signup and view all the answers

What is accurate about rare genetic variants in relation to psychosis?

They can be carried without developing psychosis. Signup and view all the answers

Which study method does not require a hypothesis to identify genetic markers for complex diseases?

Genome-Wide Association Studies (GWAS) Signup and view all the answers

Which syndrome is associated with a substantial risk of developing schizophrenia?

Velio-cardio-facial syndrome (VCFS) Signup and view all the answers

What is true about the 270 common genetic variants associated with schizophrenia?

They convey a subtle increase in risk. Signup and view all the answers

What role does genetic relatedness play in the risk of developing psychosis?

Risk increases with genetic relatedness. Signup and view all the answers

Study Notes

Heritability of Psychosis

Psychosis has a high heritability rate (80%).
Risk of psychosis increases with genetic relatedness to an affected individual.
Increased risk is due to genetic factors, not just shared environment.

Risk Factors for Psychosis

Genetic: Copy Number Variants (CNVs), common single nucleotide polymorphisms (SNPs).
Environmental: Migration, cannabis use, childhood adversity/abuse, urban birth/upbringing, obstetric complications.

Genetic Inheritance of Psychosis

Psychosis is a complex genetic disorder, not following Mendelian inheritance patterns.
Caused by multiple genetic and environmental factors, and their interactions.
Similar to other complex traits like height, weight, blood pressure, IQ.

Identifying Genetic Variants

Genome-Wide Association Studies (GWAS): Examine millions of genetic markers (SNPs).
Sequencing: Examines entire DNA sequence, doesn't require hypotheses.

Common Genetic Variations

Common variants: Small individual effects, hard to identify.
Rare variants (CNVs): Genomic deletions/duplications, substantial risk factors for schizophrenia (e.g., VCFS).
CNVs: Are part of normal variation, not always penetrant (not all carriers develop psychosis), and not necessary or sufficient for the disorder.

Genetic Variants and Risk

VCFS (velo-cardio-facial syndrome): Deletion increases the risk of schizophrenia and, possibly bipolar disorder, accompanied by intellectual disability and autism.
270 common SNPs: Individually increase schizophrenia risk.
10 rare SNVs (single nucleotide variants): Show significant association with schizophrenia.
22q11.2 (CNV): Deletion increases bipolar disorder risk.

Predicting Psychosis

Accurate psychosis prediction isn't possible.
Polygenic Risk Scores (PRS) can estimate the genetic predisposition to psychosis.
PRS combines all SNPs to evaluate schizophrenia (9% variance) or bipolar risk (2% variance).
PRS is a predictor of risk.

Endophenotypes

Endophenotypes are quantitative measures of brain function/structure, like biomarkers.
They are heritable, strongly associated with the illness, safe, and noninvasive.
Examples include enlarged ventricles on MRI, EEG changes (P300 wave), and cognitive functions (verbal/spatial learning).
Endophenotypes help understand mechanisms, improve classification, and personalize treatment strategies.

Clinical Implications

SNPs increase the risk of schizophrenia OR bipolar, some increase risk of both.
Small-effect SNPs can influence drug development.

Genetic Counseling

Provides information about genetic conditions, inheritance patterns, risks, treatments, and adjustment strategies.

Pharmacogenomics

Genetic tests to personalize treatment for more than 20 antipsychotics to tailor treatment response and side effects.

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Description

Explore the genetic and environmental factors contributing to psychosis. This quiz covers heritability rates, genetic variants, and risk factors associated with the disorder. Test your understanding of the complex interplay between genetics and environment in psychiatric conditions.