lkm_n_covariates. age and sex for 20 samples, each one has 5 time points
lkm_n_gene. genotypes for 20 samples for two genes and each gene has 50 SNPs
lkm_n_gid. ordered sample id as in lkm_n_gene (20 samples)
lkm_n_weights. weight for each SNP
lkm_n_y. sample id, trait and time points