it can influence a regulation process since it may change a binding site for a transcriptional factor or an RNAi 

one way is that the base change in the intron creates a better splice site than the natural one so the protein produced is either too long or too short depending on which splice site is produced

most disease-causing mutations occur within a gene's coding or regulatory regions and affect the function of the protein encoded by the gene. Unlike mutations, SNPs are not necessarily located within genes, and they do not always affect the way a protein functions. SNPs are divided into two main categories:

Linked SNPs (also called indicative SNPs) do not reside within genes and do not affect protein function. Nevertheless, they do correspond to a particular drug response or to the risk for getting a certain disease.

Causative SNPs affect the way a protein functions, correlating with a disease or influencing a person's response to medication. Causative SNPs come in two forms:

Coding SNPs, located within the coding region of a gene, change the amino acid sequence of the gene's protein product.

Non-coding SNPs, located within the gene's regulatory sequences, change the timing, location, or level of gene expression.