Figure 1  .

Interleukin 1 receptor antagonist gene (IL-1RN) +2018 exon 2 single nucleotide polymorphism genotyping using restriction enzyme digestion of amplified polymerase chain reaction (PCR) products. Lane 1 contains a standard DNA ladder. Lanes 2-7 contain DNA from three individuals. Amplified PCR products from each individual were divided into two aliquots and separately digested with AluI or MspI. PCR products were size fractionated by 9% polyacrylamide gel electrophoresis and visualised under ultraviolet light after staining with ethidium bromide. The two enzymes cut the two alleles differently. AluI cuts the 154 base pair fragment to produce 126 and 28 base pair fragments in allele 1 while it does not digest allele 2 (154 base pairs). MspI digestion produces 125 and 29 base pair fragments in allele 2 but does not digest allele 1 (154 base pairs). Hence the two reactions (separated side by side on a gel) will give inverted patterns of digestion for homozygous individuals (lanes 4/5 and 6/7), and identical patterns in heterozygotes (lanes 2/3).