Principles of basic methods of SNP-A and its application for karyotyping. The generalized principle behind the technology used in Affymetrix SNP-A is shown in the left portion of the figure, whereas the bead array platform used by Illumina (San Diego, CA) is depicted in the right with both 1- and 2-color variants used in Infinium I and II arrays (Illumina). Below, the principle of genotyping based on the hybridization pattern for allelic probes is shown. For a detailed description, see “Single-nucleotide polymorphism arrays.”