Figure 1

Detection and screening of the TOPBP1 *Arg309Cys substitution by (a) direct sequencing, (b) restriction enzyme analysis, and (c) 5'-nuclease allelic discrimination assay. a) Direct sequencing of the sense strand of TOPBP1 exon 8. From top to bottom: Homozygous genotype Arg/Arg, heterozygosity Arg/Cys, homozygous genotype Cys/Cys. The position of the mutation is marked by an asterisk. b) Restriction enzyme analysis after incubation with Tat I and 2% agarose gel electrophoresis. Lanes from left to right: common homozygote (Arg/Arg, 1-1), heterozygous sample (Arg/Cys, 1-2), rare homozygote (Cys/Cys, 2-2). c) 5'-nuclease allelic discrimination assay identifying common homozygotes (Arg/Arg, red circles), heterozygotes (Arg/Cys, green triangles), and rare homozygotes (Cys/Cys, blue square). NTC, no template control.