Figure 1: (a) IGH@ gene structure, VDJ rearrangement, and PCR primer annealing sites. The IGH@ gene is composed of ~45 V segments, ~23 D segments, and 6 J segments. DJ rearrangement occurs first, here combining and . This is followed by V-DJ rearrangement, here combining with the previously rearranged -. Multiple PCR primers are directed against the 3 FR regions in the V segment and a single primer to the J segment (FR4). N represents nucleotides inserted and deleted by TdT. Adapted with permission from . (b) TRG@ gene structure, VJ rearrangement, and PCR primer annealing sites. The TRG@ gene is composed of 11 V segments and 5 J segments. VJ rearrangement here combines the V6 and JP2 segments. Multiple PCR primers are directed against V segments and J segments.