What is the difference between genotyping and sequencing?
Sequencing determines the exact base pairs in a certain span of DNA, such as every ATCG in the whole prothrombin gene.
Genotyping is the process of determining which genetic variants an individual possesses. Sometimes, this is just determining which ATCG is at single location in an individual’s DNA. For example, one might genotype an individual for the most common variant of prothrombin, which is defined by a T instead of a G at position 20210 (also known as Prothrombin G20210A).
Genotyping requires prior knowledge of the variants you want to analyze, such as G20210A in prothrombin. This knowledge can change over time, depending on new discoveries (for example a new clinically relevant mutation in prothrombin). In such cases, individuals would need to be re-genotyped. However, if one sequenced the entire gene, one could look for new variants in the existing sequencing data since every base pair in that gene would be known.