Gene tests may be beneficial in cases of suspected hereditary heart disease or hyperlipidemia. A gene defect can be found in approx. 20% of those with hypertrophic cardiomyopathy in Finland. In the long QT syndrome, four major mutations account for almost three fourths of the Finnish cases. The gene defect causing familial hypercholesterolemia is found in approx. 90% of cases. If the familial gene defect is revealed, DNA testing can be applied to find the symptomless carriers of the mutation who require follow-up, and to liberate those not carrying the mutation from the follow-up.