Single Nucleotide Polymorphisms and diseases
SNPs in all these regions will modify the DNA sequence. Effects will depend on where exactly the SNP is. I'll summarize the conditions in which effects can be maximum


Transcription Factors (TFs) binding sites: SNP in the nucleotide positions that bind to the recognition amino acids in the TF
Epigentic signals: C->X [x: A,G,T] SNPs can disrupt DNA methylation hotspots
Splicing variants: SNPs at splice donor/acceptor sites can cause intron retention
microRNA binding sites: SNP in seed region can abolish miRNA targeting
Coding regions: certain SNPs can create premature stop codons for e.g. CAG (Gln) -> UAG (stop)


there is a lot of work on SNPs. If you search in pubmed for all these categories, you'll get many research articles as well as reviews.