SNPs are causal in that they can be thought of as perturbations of genes that occur prior to the genesis of the phenotype. I think what you might be trying to

SNPs are causal in that they can be thought of as perturbations of genes that occur prior to the genesis of the phenotype. I think what you might be trying to say is (1) the presence of a SNP may not be sufficient for the occurrence of a phenotype, or (2) another SNP in high LD may be the true causal SNP.