Genotyping refers to the process of determining the genotype of an individual with a biological assay. Current methods of doing this include PCR, DNA sequencing, and hybridization to DNA microarrays or beads. The technology is intrinsic for test on father/motherhood and in clinical research for the investigation of disease-associated genes.

Due to current technological limitations, almost all genotyping is partial. That is, only a small fraction of an individual’s genotype is determined. New innovations, like the Human-1 BeadChip developed by Illumina promise to provide whole-genome genotyping in the future.

When testing for father-/motherhood, scientists typically only need to look at 10 or 20 genomic regions (like Single nucleotide polymorphism (SNPs) to determine relationship or lack thereof. That is a tiny fraction of the human genome, which consists of three billion or so nucleotides.

When genotyping transgenic organisms, a single genomic region may be all that scientists need to look at to determine the genotype. The mouse is the mammalian model of choice for much of medical research today. A single PCR assay is typically enough to genotype a transgenic mouse. Companies that provide mouse genotyping services include GeneTyper,TransnetYX and Mouse Genotype LLC.