F₂ Data in Repulsion Phase Linkage

Only one of sixteen possible genotypes provide information regarding recombination frequency for F₂ families with complete dominance gene action and coupling phase linkage. This shows that coupling data is of more value than repulsion data for estimation of linkage intensity when the number of genotypes scored and the map distance are both constants. The parental gametes in repulsion phase linkage are Gh and gH. The recombinant gametes are GH and gh.

The genotypes which are not in bold are not informative because of dominance gene action. For the 15 genotypes that are not in bold print we cannot determine whether the genotype is the result of two non- recombinant gametes that have united to form a zygote or whether the genotype is the result of a recombinant and non-recombinant gamete which have united to form a zygote.

from Appels, R., R. Morris, B. Gill, and C. May. 1998. Chromosome Biology. pg. 328. Kluwer Academic Publishers, London.