The A1/B1 and C1/D1 PCR products can be sequenced using primers A1/A2/A4/B1/B2/B4 and C1/C2/D1/D2/D4, respectively. As a first step, use primers A1/ B1 and C1/D1 for sequencing unless there are problems in getting a continuous sequencing read. Should this problem be encountered, more focused sequencing reads can be performed using primers A2/A4/B2/B4 and C2/D2/D4.