Genetic Association Studies in Psychiatry

Questions and Answers

What is the primary goal of a genome-wide association study (GWAS)?

To replicate previous genetic findings in a different population

To ensure the accuracy of genotyping methods

To uncover the genetic basis of a given disease (correct)

To identify previous genome sequences of rare variants

Which term describes the non-random assortment of alleles at multiple loci?

Phenotypic Plasticity

Linkage Disequilibrium (correct)

Genotype Frequency

Allelic Variation

In the context of genetic association studies, what does 'imputation' typically refer to?

Analyzing linkage disequilibrium patterns

The process of removing erroneous genotype data

Estimating unobserved genotypes based on known data (correct)

Creating a new SNP marker map from scratch

What model is primarily used to analyze common genetic variants in relation to trait effects?

Additive Effects Model Signup and view all the answers

How are common SNPs selected for genome-wide studies?

By accounting for linkage disequilibrium in a tag set Signup and view all the answers

Which of the following best describes the role of multiple technical challenges in GWAS?

To accurately assess genetic associations across the genome Signup and view all the answers

What is an important characteristic of markers in strong linkage disequilibrium?

They co-segregate within families and populations Signup and view all the answers

What represents the typical increase in the number of genetic variants after a GWAS through imputation?

From 500K-1M to 6-12M variants Signup and view all the answers

What is one major ambition of the genomic era as indicated in the content?

To use genetics for predicting human traits and diseases Signup and view all the answers

What do Genome-Wide Association Studies (GWAS) primarily focus on?

Searching for genetic variants associated with diseases Signup and view all the answers

Which of the following traits could potentially be predicted using genetic information?

Height and blood pressure Signup and view all the answers

Which of these is NOT a focus of the genomic era according to the content?

Creating a universal vaccine for all diseases Signup and view all the answers

What aspect does the lecture outline suggest will be covered after discussing GWAS?

From discovery to prediction in genetics Signup and view all the answers

Which of the following would likely be a key topic in studying Polygenic Risk Scores for Medical Research?

The cumulative effect of multiple genetic factors on disease risk Signup and view all the answers

In the context of GWAS, what is indicated by the term 'discovery sample size'?

The number of individuals included to identify associations Signup and view all the answers

Which statement about Crohn's disease and other conditions mentioned is most likely correct?

They have been extensively studied with large sample sizes. Signup and view all the answers

What is a primary characteristic of polygenic disorders compared to Mendelian genetic traits?

They are influenced by multiple genes and their variants. Signup and view all the answers

Which statement correctly describes the focus of Genome-Wide Association Studies (GWAS)?

GWAS investigates associations between genetic variants and complex traits. Signup and view all the answers

What is one significant difference between sequencing and genotyping in the context of genetic research?

Sequencing provides a comprehensive view of all genetic variations while genotyping targets specific variants. Signup and view all the answers

What is the main implication of the statement 'each gene usually has a tiny effect' in relation to complex diseases?

Multiple genes collectively contribute to the risk of developing the disease. Signup and view all the answers

In what context does the population impact of polygenic disorders differ from Mendelian disorders?

Polygenic disorders tend to have a high population impact, while Mendelian disorders have a low population impact. Signup and view all the answers

Which of the following best describes the term 'genetic variations'?

They are changes in the DNA code that do not typically lead to disease on their own. Signup and view all the answers

Why is there a need for stronger research bases for polygenic risk scores to be applied in routine clinical care?

The implications of these scores are unclear for individual patient care. Signup and view all the answers

What is a significant challenge in moving polygenic risk scores into routine clinical practice?

Validating their predictive power for individual conditions remains limited. Signup and view all the answers

Study Notes

Background

Mendelian traits are caused by single genes, while polygenic disorders involve multiple genes.
Mendelian disorders include Huntington's disease, cystic fibrosis, and Zellweger syndrome.
Polygenic disorders include asthma, cancer, depression, and coronary heart disease.
Mendelian traits have high individual impact but low population impact, whereas polygenic traits show a high population impact with low individual impact.

Genome-Wide Association Studies (GWAS)

GWAS aim to uncover the genetic basis of diseases by examining common genetic variations across the genome.
The studies look for associations between SNP genotypes and disease status.
Key technical challenges have been addressed to enhance GWAS reliability.

Genetic Association Testing

Genetic association testing identifies genetic variants associated with complex traits, often involving many variants with small effects.
Different alleles at a single nucleotide polymorphism (SNP) can influence disease risk.
The effects of genotypes on phenotypes are categorized into inheritance models, demonstrating additive effects for common variants.

Linkage Disequilibrium

Linkage disequilibrium refers to the non-random assortment of alleles at two or more loci, highlighting correlations between genetic variants.
Markers in strong linkage disequilibrium co-segregate within families and populations, facilitating SNP selection for studies.

SNP Selection and Imputation

GWAS require a representative set of common SNPs that account for linkage disequilibrium to capture most genetic variation.
Imputation is used to increase the number of genetic variants analyzed, transforming 500K-1M genotyped SNPs into 6-12M imputed + genotyped variants.

GWAS Discoveries and Sample Size

Larger sample sizes yield more GWAS hits for identifying genetic associations across traits like height and various diseases (e.g., Crohn's disease, breast cancer).
Successful GWAS studies often correlate the number of genetic variants discovered with sample sizes.

From Discovery to Prediction

The genomic era's goal is to leverage genetic information for predicting individuals' risks for diseases and traits, leading to personalized medicine.
Genetics can help predict traits beyond disease, including physical characteristics and behavioral tendencies.

Polygenic Risk Scores

Polygenic risk scores combine multiple genetic variants to estimate an individual's risk of developing specific diseases.
Enhanced understanding of polygenic traits necessitates a stronger research base for clinical applications.

Personalized Medicine

Advancements in genetic research enable the potential integration of personalized or precision medicine, tailoring healthcare based on an individual's genetic makeup.

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Description

Explore the concepts of Genome-Wide Association Studies (GWAS) and polygenic risk scores as discussed by Professor Gerome Breen. This quiz covers the foundational background of disease genes, genetic association testing, and inheritance models critical in psychiatric genetics.