Electrophoresis of products of allele-specific PCR for N363S and PCR-RFLP of Bcl I and ER22/23EK polymorphisms. A: Allele-specific PCR reaction yielded a control fragment of 357 bp in each tube and a specific fragment of 306 bp in those tubes where the mutant allele (coding serine) was present. C1 indicates a wild-type homozygous control. C2 indicates a heterozygous control sample. P1 and P8 are patients carrying the polymorphism N363S. P2-P7 and P9 are samples of wild-type patients. A band of 357 bp served as internal control in each reaction. B: RFLP analysis using BclI restriction enzyme resulted in fragments of 263, 151 bp for wild-type homozygous samples (C1, P2-P5, P8), fragments of 418, 263 and 151 bp for heterozygous samples (C2, P1, P6-P7), and a 418-bp-long fragment for polymorphic homozygotes (C3). C: Analysis of ER22/23EK using MnlI restriction enzyme resulted in fragments of 149 and 163 bp for wild-type homozygous samples (C1, P1-P9), and fragments of 163 and 184 bp for heterozygous samples (C2). Abbreviations: M=molecular weight marker, bp=base pair, C1-3=control, P1-P9=patients.