What is the difference between genotyping and sequencing?

Though you may hear both terms in reference to DNA, genotyping and sequencing refer to slightly different techniques.

Genotyping is the process of determining which genetic variants an individual possesses. Genotyping can be performed through a variety of different methods, depending on the variants of interest and the resources available. For looking at many different variants at once, especially common variants, genotyping chips are an efficient and accurate method. They do, however, require prior identification of the variants of interest, and are limited to a very small percentage of the genome, typically through microarray technology.

Sequencing is a method used to determine the exact sequence of a certain length of DNA. You can sequence a short piece, the whole genome, or parts of the genome (such as the “exome," which are the regions of the genome that contain the the instructions for RNAs (ribonucleic acid) and proteins). Depending on the region, a given stretch of sequence may include some DNA that varies between individuals, in addition to regions that are constant. Thus, sequencing can be used to genotype someone for known variants, as well as identify variants that may be unique to that person.

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