The lod score reflects the odds that two loci are linked with a given recombination fraction. Lod scores can be summed across families.


For a given recombination fraction (theta) and a family with both nonrecombinant and recombinant offspring and phase known meioses:


lod score for given theta =

= ((total number of children) * LOG10(2)) + ((number of nonrecombinants) * LOG10(1 - (theta))) + ((number of recombinants) * LOG10 (theta))



• theta = recombination fraction = recombination between the disease locus and the DNA marker locus tested

• The values of theta range from 0 to 0.5.



• A value for theta of 0.5 indicates that the loci are unlinked.

• An lod score >= 3.0 indicates that there is statistically significant evidence of linkage.

• An lod score from -2.0 to +2.9 are inconclusive.

• An lod score < -2.0 is evidence against linkage.


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