Rights: © Dr Jeff Upton, Canterbury Health Laboratories, Christchurch, New Zealand Published 3 September 2009 Size: 27 KB

A simple genetic test for lactose intolerance uses DNA from blood samples, which is amplified and digested with restriction enzymes. The pattern of DNA fragments indicates whether a person is lactose intolerant (C/C) or lactose tolerant (C/T or T/T).