Genotyping refers to the process of determining the genotype of an individual with a biological assay (e.g., PCR-RFLP, DNA sequencing, hybridization to DNA chips or beads) (http://en.wikipedia.org/wiki/Genotyping). We are currently using the PCR – RFLP (Polymerase chain reaction - Restriction Fragment Length Polymorphism) method to detect genetic variation in the human population. After DNA isolation from whole blood by means of the QIAamp DNA blood Mini/Midi Kits (QIAGEN), the region of DNA containing the mutation of interest is amplified by simplex or multiplex PCR. The PCR product is further cleaved by a restriction enzyme which cuts either the wild type or the mutant allele at the polymorphic site. Separation of the digestion products by gel electrophoresis and visualization of the DNA fragments with ethidium bromide under UV-light allows detection of the individual genotypes.