Figure 1: PCR analysis of the 4G/5G insertion/deletion polymorphism of the human PAI-1 promoter. Genotyping was performed by PCR analysis using 1.5% agarose electrophoresis using a common downstream primer, a control primer (generating a 257 bp PCR product), and two allele-specific upstream primers, generating a 139 bp PCR product. For each individual, two PCR reactions (control primer, common downstream primer, and 4G-allele-specific primer or 5G-allele-specific primer, respectively) were performed. Some samples of the amplified DNA of 5G PCR using the ‘insertion’ primers for the PDR patients are shown. Patients in lanes 1, 2, 3, 5, 6, 9, 11, 14, 15, 18, 20, 21 had a 5G band at 139 bp and a control band at 257 bp. Lanes 4, 8, 10, 12, 13, 16, 17, 19 had a control band at 257 bp and no 5G band. Lane 7 shows no band for control or for amplified 5G (failure of DNA amplification). Fragment lengths are indicated by an arrow. M, ØX174 HaeIII molecular weight marker; PDR, proliferative diabetic retinopathy.