Genetic Variations: SNPs in Coding and Noncoding Regions

Questions and Answers

Where do SNPs mainly occur in the genome?

Intergenic regions

What percentage of SNPs is found in coding regions?

How can SNPs located in noncoding regions influence disease susceptibility?

By affecting gene expression

What is the term used for SNPs thought to have no effect on gene function or individual phenotype?

Neutral variants Signup and view all the answers

In what situation can 'neutral' SNPs still be useful markers according to the text?

When they are physically close to a disease-associated polymorphism Signup and view all the answers

What is the likelihood of SNPs occurring in coding regions based on their proportion in the genome?

Equal to what would be expected by chance Signup and view all the answers

What is the primary mechanism by which 'neutral' SNPs can be used as markers for disease susceptibility?

They are in linkage disequilibrium with a disease-associated polymorphism Signup and view all the answers

What is the typical effect of most SNPs on disease susceptibility?

Weak and indirect Signup and view all the answers

What is the term used to describe the physical proximity of a neutral SNP and a disease-associated polymorphism?

Linkage disequilibrium Signup and view all the answers

What is the main characteristic of complex rearrangements of genomic material in CNVs?

They involve multiple variants in the human population Signup and view all the answers

What is the size range of the contiguous stretches of DNA involved in CNVs?

1000 base pairs to millions of base pairs Signup and view all the answers

What is the main difference between 'neutral' SNPs and other SNPs?

Their effect on gene function Signup and view all the answers

What is the potential use of identifying SNPs, alone or in combination, in the context of disease prevention?

Developing effective strategies to identify those at risk Signup and view all the answers

What is the relationship between the physical proximity of a neutral SNP and a disease-associated polymorphism, and their coinheritance?

The proximity results in the coinheritance Signup and view all the answers

What is the implication of the weak effect of most SNPs on disease susceptibility?

The effect of multiple SNPs may be strong Signup and view all the answers

Study Notes

SNPs

SNPs occur throughout the genome, including exons, introns, intergenic regions, and coding regions.
Only about 1% of SNPs are found in coding regions, which is roughly what would be expected by chance, given that coding regions make up about 1.5% of the genome.
SNPs in noncoding regions can affect gene expression by altering genomic regulatory elements, directly influencing disease susceptibility.
"Neutral" SNPs are thought to have no effect on gene function or individual phenotype.
Even "neutral" SNPs can be useful markers if they are coinherited with a disease-associated polymorphism due to physical proximity, resulting in linkage disequilibrium.
The impact of most SNPs on disease susceptibility is relatively weak.

CNVs

CNVs (Copy Number Variations) are a type of genetic variation characterized by different numbers of large, contiguous stretches of DNA, ranging from 1000 base pairs to millions of base pairs.
CNVs can be biallelic, resulting in simple duplications or deletions in some individuals.
Complex rearrangements of genomic material can occur at other sites, with multiple variants present in the human population.