HLA-A typing can be used to investigate the zygosity of twins.
The famous fictional detective Sherlock Holmes stated, “It has long been an axiom of mine that the little things are infinitely the most important.” We are interested in how DNA is used to solve crimes and other mysteries. For example, how can you tell for sure whether a pair of twins is identical or fraternal? We recently looked into this question by using PCR to type at the HLA-A gene, which has about 1939 different alleles. We have also used DNA typing on dogs and horses!