Examples of TCR repertoire similarities within individual LGL patients. Freq indicates clonotypic frequency as the number of identical clonotype sequences divided by total number of clones; and VB-JB, restriction of a given variable and joining beta chain of the TCR. Solid boxes indicate nucleotide exchanges resulting in AA exchange (the affected AAs are highlighted in yellow); dashed boxes and lines, nucleotide exchanges that do not lead to AA exchanges. ‡Total of 11 similar exchanges were found and were not included in the analysis, due to the possibility of Taq-polymerase–generated errors. Of interest, in patient 44 an immunodominant clonotype has 2 “supporting” clonotypes that differ in only 1 amino acid of the CDR3 sequence. Those 2 clonotypes were translated from 2 different nucleotide sequences each (*). In both cases the underlying sequences differed in 2 nucleotides that did not affect the AA sequence. Although we postulate that single nucleotide exchanges reflect Taq-polymerase reading errors, in this case the accumulation of nucleotide substitutions indicates that the 5 shown clones in patient 44 may have resulted from independent rearrangement events.