If offspring of a parent inherit one of two genotypic combinations but the phase of meiosis is unknown, then either one or the other is recombinant while the other is nonrecombinant. The calculation of the lod score in this situation is similar to that for phase known meiosis, except for the additional possibility that alleles were in repulsion.


lod score for given theta =

= ((total number of children) * LOG10(2)) + (LOG10(((((theta) ^ B) * ((1 - (theta)) ^ A)) + (((theta) ^ A) * ((1 - (theta)) ^ B))) / 2))



• A = first group of genotypic offspring

• B = second group of genotypic offspring

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

• The values of theta range from 0 to 0.5.


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