Resources for understanding haplotype blocks and linkage disequilibrium?

In summary, linkage disequilibrium is a phenomenon where by knowing the state of one marker, you can predict the state of the other. This could be because they are located next to each other on a chromosome (linked) or because the two markers interact together in another way. Haplotypes are blocks of markers that are inherited together due to low recombination rates, and by determining a single marker (a SNP for instance), you can determine the state of the others on that block: LD. This is useful, because it reduces the amount of markers that need to be analyzed for a genetic map.
  • #1
gravenewworld
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Does anyone know of any good resources online of where I can get clear and simple explanations on this subject? I don't want to read journal articles about this or want websites with heavy duty math since I don't have time to go through all of that right now in that kind of depth. I just want a simple website that explains the relationships between SNPs and haplotypes and how they can be used to make a genetic map based on their linkage disequilibrium. I am having an awful time trying to understand this how this works.
 
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  • #2
What don't you understand? Linkage equilibrium would mean the random association of genetic markers: if you'd know the state of one you don't know it of the other.

Linkage disequilibrium (LD) then means that by knowing the state of one marker, you can predict the state of the other. This could be because they are located next to each other on a chromosome (linked) or because the two markers interact together in another way.

Haplotypes are blocks of markers that are inherited together due to low recombination rates are called haplotype blocks. By determining a single marker (a SNP for instance), you can determine the state of the others on that block: LD. This is useful, because it reduces the amount of markers that need to be analyzed for a genetic map.

Does that make sense to you?
 
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  • #4
Here's another link that is pretty informative. About twenty minutes on that page should give you a pretty solid understanding:

http://www.genome.gov/10001665
 
  • #5
Thanks for the responses. They helped me out quite a bit.
 

Related to Resources for understanding haplotype blocks and linkage disequilibrium?

1. What are haplotype blocks and how are they defined?

Haplotype blocks are regions of the genome where a set of alleles are inherited together. These blocks are defined by a certain measure of linkage disequilibrium, which is the non-random association of alleles at different loci on a chromosome.

2. How do haplotype blocks affect genetic diversity?

Haplotype blocks can greatly affect genetic diversity by limiting the number of combinations of alleles that can be inherited together. This can lead to a decrease in genetic variability within a population, making it more susceptible to diseases or environmental changes.

3. What is the relationship between haplotype blocks and population history?

The distribution and size of haplotype blocks can provide insights into the population history of a species. For example, larger blocks may indicate a recent population bottleneck, while smaller blocks may suggest a larger and more diverse ancestral population.

4. How are haplotype blocks and linkage disequilibrium measured?

Haplotype blocks are measured using various statistical methods, such as haplotype frequency, haplotype diversity, and haplotype homozygosity. Linkage disequilibrium is typically measured using the statistics D' and r2.

5. How can understanding haplotype blocks and linkage disequilibrium be useful in genetic studies?

Understanding haplotype blocks and linkage disequilibrium can help identify genetic variants that are associated with certain diseases or traits. It can also aid in the design of genetic studies and the interpretation of results, as well as informing our understanding of evolutionary processes and population history.

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