A nonparametric and a parametric version of a test for the detection of the presence of a major gene applicable on data for the complete nuclear family.

Nonparametric and parametric tests are suggested for detecting the presence of a major gene for a quantitative trait. The model for the determination of the quantitative trait is an additive one with polygenic, family environment, and individual environment components. The power functions with respect to the major gene effect have been calculated by simulation, and the tests have therefore been compared with each other. The tests have been applied to nuclear family data on human obesity, and the results compared with those obtained using other methods on the same data.