Hi,

Under interference, the number of crossovers occurring is no longer Poisson, for example, for a triple backcross (ABC/abc x abc/abc) progeny (when ABC is the order of the loci ),

1. under no interference, the expected frequency for the geneotype AaBbCc is 0.5(1-r1)(1-r2), where r1 and r2 are the recombination rate between locus(1--2) and locu (2–3) respectively.

2. Under interference, the expected frequency for the geneotype AaBbCc is 0.5 (1-r1-r2-Cr1*r2), where C is the coefficient of coincidence. How does this come and what about four loci for example .