Using the ABO blood type system as an example, the frequency of one of the alleles, for example I A , is the number of copies of that allele divided by all the copies of the ABO gene in the population...Using the ABO blood type system as an example, the frequency of one of the alleles, for example I A , is the number of copies of that allele divided by all the copies of the ABO gene in the population, i.e. For example, in a sample population of humans, the frequency of the I A allele might be 0.26, which would mean that 26% of the chromosomes in that population carry the I A allele.
