Figure 2: (a) Heatmap of T - cell receptor beta variable (TRBV) allele profiles for 81 Caucasians. T - cell receptor beta (TCRB) repertoires were used to construct variable gene allele profiles for each individual. The sets of alleles detected for each individual are displayed in heatmap form, where each row represents a different individual, and each column a different variable gene allele. Red tiles indicate that an allele was detected in an individual while blue tile indicates allele absence. Columns are arranged through hierarchical clustering, while rows are arranged according to haplotype group classification produced by k-means clustering. IMGT allele names are displayed along the X-axis; alleles having a lowercase 'p' in the name correspond to putative novel alleles absent from the IMGT database. To the left, Cluster column indicates the haplotype group classification. (b) Principal component (PC) analysis of allele profiles. Samples are displayed according to the two largest principal components derived from analysis of the TRBV allele profile matrix. Samples are colored according to haplotype group classification identified through k-means analysis. (c) Within cluster sum of squares following subdivision of data into 2 to 15 clusters through k-means analysis of sample set. (d) Number of distinct alleles detected across haplotype groups. The number of distinct alleles detected in each individual was calculated then displayed according to haplotype group. (e) Number of uncommon alleles detected across haplotype groups. Uncommon alleles are defined as those found in <50% of this Caucasian cohort. IMGT: ImMunoGeneTics.