Illustration of interpretation of evidence for chimerism. The histogram shows the frequency of relative intensity values for allele 1 using only hair-derived DNA from the combined Holstein and Jersey populations for 1 SNP, Hapmap51593-BTA-42524. The relative intensity values cluster for the 3 genotypes, TT, CT, and CC. Solid blue lines depict the range of relative intensity values observed for each genotype. Allele 1 (allele 2) homozygotes could logically have relative intensity scores as great as 1 (as low as 0) for allele 1, thus the maximum (minimum) acceptable value for relative frequency of allele 1 (allele 2) was extended to 1 (0) (gray line). Representative chimeric (32382) and nonchimeric (32383) twins are indicated by red squares. Blood-derived DNA relative intensity value for 32382 is inconsistent with its hair-derived DNA genotype of TC, indicating chimerism. In contrast, blood-derived relative intensity value for 32383 is consistent with its hair-derived DNA genotype of TT, and its classification was nonchimeric.