We introduce a test for the overall effect of interaction between DNA methylation and a set of single nucleotide polymorphisms on a quantitative phenotype. The developed inference procedure is based on a functional approach that extend existing regression models in functional data analysis. Through extensive simulations, we show that the proposed test effectively controls type I error rates and highlights increased empirical power over existing methods, particularly when multiple interactions are present. The use of the proposed test is illustrated with an application to data from obesity patients and controls.