Genotypic information for sets of alleles or markers is frequently listed using combinations of letters and numbers. Data sets can present these genotypes in one of several formats. In the two column allelic format, each of the two alleles that make up a genotype is listed in a separate column. In the one column format, both alleles are listed in a single column. Alleles might or not be delimited and might be coded using either character or numeric values.
In the example shown below, each allele for the locus is presented in a separate column: ma1 and ma2 . This individual is heterozygous for the A and B alleles. The individual represented in this example is heterozygous at the ma1 locus. The two alleles are delimited by a “/”. The individual represented in this example is heterozygous for the A and B alleles at the ma1 locus. The two alleles are not delimited. Numeric Genotypes is selected only for SNP markers for which the two homozygotes are represented by 0 and 2, and the heterozygous genotype is represented by 1.There are three individuals represented in this example. The first is heterozygous at the ma1 locus. The second and third are homozygous , but for different alleles, at the ma1 locus. Single-Character Homozygous Genotypes 1 Note : Heterozygotes are still represented using the two-character format (for example, A/B is represented by AB ).