Inviability, Impenetrance and Linkage Detection
The study of linkage has two phases: (a) the detection of linkage among segregating genes and (b) estimation of its strength. The two phases are certainly not distinct, except in a formal sense, for the second arises naturally from a positive answer to the first. It is self-evident that at least two mutant non-allelic genes are necessary for linkage analysis and the first question which must be answered is whether or not the genes conform to the classical Mendelian ratios. That is, to the 1 : 1 or 3 : 1 ratio of a recessive gene for the testcross or intercross generation. Regardless of the presence of other genes or of linkage, each gene should occur individually in these ratios and each should be specially checked. Those genes which conform to expectation are the most useful for extended studies and, where a choice can be exercised, should be utilized.
KeywordsDominant Gene Recessive Gene Gene Ratio Linkage Phase Linkage Detection
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