## How do you find the recombination fraction?

Divide the number of recombinant offspring by the sum of the recombinant and nonrecombinant offspring. In this example, dividing 40 by 100 gives 0.4. This is the recombinant fraction.

## What does 50% recombination indicate?

A frequency of recombination of 50% indicates that the genes are independently assorting.

What does a high LOD score mean?

​LOD Score A LOD score of 3 or higher is generally understood to mean that two genes are located close to each other on the chromosome. In terms of significance, a LOD score of 3 means the odds are a thousand to one that the two genes are linked, and therefore inherited together.

### How is LOD score calculated?

The odds ratio is the probability of obtaining a particular observed concordance ratio, divided by the probability of obtaining that ratio at random. [The concordance probability is also influenced by allele frequencies at the locus, which are set here at a constant θ = 0.8]. Then, the LOD score = log 10 (odds ratio).

### Where do you find Centimorgans?

23andMe: You can see the percentage of shared DNA from the main DNA Relatives home page. To convert the percentage into centimorgans, just multiply your percentage by 68 (that will at least get you close). You can also see total shared cMs in the chromosome browser tool (go to Tools > DNA Relatives > DNA).

What does a recombination frequency of 20% indicate?

In this case, the value is 0.20 times 100, or 20%. The lower the recombination frequency, the more closely the genes are physically linked. Think about it like this: The closer genes are to each other on a chromosome, the closer they are physically.

#### What does a low recombination frequency mean?

The greater the frequency of recombination (segregation) between two genetic markers, the further apart they are assumed to be. Conversely, the lower the frequency of recombination between the markers, the smaller the physical distance between them.

#### What does a LOD score of 0 mean?

When the peak Lod Score occurs at θ equal to zero, i.e., no recombination between the genes, this indicates that two genes are located very close together. Thus the Lod Score is a measure of linkage while the recombination frequency is a measure of distance between two linked genes.

Can you get a negative LOD score?

The LOD score compares the likelihood of observing your data if the two loci (your marker and disease loci) are linked, to the likelihood of observing the same data purely by chance. Positive LOD scores favor the presence of linkage, whereas negative LOD scores indicate that linkage is less likely.

## What does a LOD score of 2 mean?

If a lod score of -2 was observed, then the null hypothesis that c=50% is 100 times more likely than the alternative c=10%. Lod scores are a popular summary of a likelihood because they are easily added (representing multiplication of the “raw” likelihoods) across observations and pedigrees.

## Can you add LOD scores?

Combining LOD Score Information across Families The individual LOD scores can be generated for each family and added together (Table 10-1). Because the maximum LOD scoreZmax exceeds 3 at θmax = ≈0.06, the RP gene in this group of families is linked to locus 2 at a recombination distance of ≈0.06.