Determining Genotype

Genotyping is the process of ellucidating the genotype of an individual with a biological assay. Also known as a genotypic assay, techniques include PCR, DNA fragment analysis, ASO probes, sequencing, and nucleic acid hybridization to microarrays or beads. Several common genotyping techniques include Restriction Fragment Length Polymorphism (RFLP), Terminal Restriction Fragment Length Polymorphism (t-RFLP), Amplified Fragment Length Polymorphisms (AFLP, and Multiplex Ligation-dependent Probe Amplification (MLPA). DNA fragment analysis can also be used to determine such disease causing genetics aberrations as Microsatellite Instability (MSI) Trisomy or Aneuploidy, and Loss of Heterozygosity (LOH). MSI and LOH in particular have been associated with cancer cell genotypes for colon, breast, and cervical cancer. The most common chromosomal aneuploidy is a trisomy of chromosome 21 which manifests itself as Down Syndrome. Current technological limitations typically allow only a fraction of an individual’s genotype to be determined efficiently. Typical results for PCR genotyping can be found at GeneTyper.