I have a data set of dimensions 19000 x 288, where there are 19000 transcripts (variables) and 288 observations. The observations correspond to 32 individuals from two countries (16 from Kenya, 16 from Scotland). The data was recorded at 8 time points, where time point 1 is the reference. I want to perform multiple testing using lasso, but be able to evaluate the difference of significant transcripts over time for each country. How do I specify this using the package glmnet in R for example?