Set-up of the genotyping on agarose gels . The figure illustrates the usual setup for the running of pcr products on agarose gels. Twelve DNA samples (including two "H37Rv" control lanes) are typed at two loci. A 100 bp ladder size marker lane (L) flanks both sides of each group of 6 PCR products. The experiment shown is part of a reproducibility test. The ten blinded-coded samples are numbered from one to ten (percy59, percy55, percy40, percy189a, percy122, percy33, percy28b, percy33b, percy31, percy53). The number of units is easily deduced from the pattern observed, the largest alleles contain six copies of the repeat unit.