Research from the laboratory of Jennifer Graves used qPCR and SNP analysis of BACs containing various genes from X chromosomes in order to find whether multiple alleles for particular X-linked genes were being expressed at once, or were otherwise being dosage compensated.
22.
It is now appreciated that most or all gene loci are highly polymorphic, with multiple alleles, whose frequencies vary from population to population, and that a great deal of genetic variation is hidden in the form of alleles that do not produce obvious phenotypic differences.
23.
The best known of these is due to the "'extended black "'mutation " E ", which is the most dominant of the multiple alleles at the " E " locus and is primarily responsible for the completely black plumage of most breeds of fowl.
24.
It is suspected that a human female could inherit multiple alleles for color blindness as protanomaly, deuteranomaly, and / or tritanomaly leading to the phenotypic expression of at least four and possibly as many as six types of color-sensing cones, although the red-, green-, and blue-deficient cones would have degenerate spectral sensitivity.
25.
In Agaricomycotina, bipolar organisms mostly have multiple alleles for their " A " mating locus; however, in Ustilaginomycotina and Pucciniomycotina, the " b " mating locus is predominantly diallelic, which reduces the occurrence of outcrossing within these species . or 2 ) both mating loci have become physically linked such that they now act as a single locus; this has occurred in the smut plant pathogen " U . hordei " and in the human pathogen " Cryptococcus neoformans ".
26.
Any individual has one of six possible genotypes ( I A I A, I A i, I B I B, I B i, I A I B, and ii ) that produce one of four possible phenotypes : " Type A " ( produced by I A I A homozygous and I A i heterozygous genotypes ), " Type B " ( produced by I B I B homozygous and I B i heterozygous genotypes ), " Type AB " produced by I A I B heterozygous genotype, and " Type O " produced by ii homozygous genotype . ( It is now known that each of the A, B, and O alleles is actually a class of multiple alleles with different DNA sequences that produce proteins with identical properties : more than 70 alleles are known at the ABO locus.
