Genotype analyses of GSTM1, GSTT1, andGSTP1.

Left panel: Agarose gel electrophoresis of PCR products from a multiplex PCR experiment for simultaneous assessment of GSTM1and GSTT1 status.33 The PCR products amplified from the GSTM1 and GSTT1 loci are 219 bp and 480 bp in size, respectively. A 268 bp fragment from the β-globin locus was coamplified for internal control purposes. Lane 1 shows an individual with a homozygous deletion of GSTM1 and GSTT1. Lane 2 shows an individual in which GSTM1 can be detected butGSTT1 is homozygously deleted. In lane 3, GSTM1 is absent while a PCR product from the GSTT1 locus can be detected. In lane 4 both GSTM1 and GSTT1 are present. M = DNA size standard. Middle and right panel: Detection ofGSTP1 codon 105 and codon 114 genotypes by agarose gel electrophoresis of PCR products after digestion with the restriction endonucleases BsmAI and AciI, respectively.10 34 The sequence polymorphism at GSTP1 codon 105 creates a restriction site for BsmAI within the resulting 176 bp PCR product, leading to the generation of 2 fragments of 91 bp and 85 bp, respectively. Thus, in individuals homozygous for this polymorphism (Val₁₀₅/Val₁₀₅) the 176 bp PCR product is completely digested into 2 fragments (lane 1). Lane 2 displays a heterozygous individual (Ile₁₀₅/Val₁₀₅), and in lane 3 an individual homozygous for the Ile₁₀₅-coding allele is shown. The polymorphism at GSTP1 codon 114 leads to the loss of an AciI restriction site. Thus, individuals homozygous for the Val₁₁₄ allele only show the undigested 217 bp PCR product (lane 1). Heterozygous individuals (Ala₁₁₄/Val₁₁₄) show the undigested product and 2 additional fragments (121 bp and 96 bp) resulting from its digestion (lane 2), and individuals homozygous for Ala₁₁₄ are characterized by the sole presence of the digestion products of 121 bp and 96 bp (lane 3). M = DNA size standard.