Editing Human variability (section)

====Single-nucleotide polymorphism====
{{Main|Single-nucleotide polymorphism}}
[[Single-nucleotide polymorphism]] or SNPs are variations of a single [[nucleotide]]. SNPs can occur in [[Coding region|coding]] or [[Noncoding DNA|non-coding]] regions of genes and on average occur once every 300 [[nucleotide]]s.<ref>{{Cite web|url=https://ghr.nlm.nih.gov/primer/genomicresearch/snp|title=What are single nucleotide polymorphisms (SNPs)?|last=Reference|first=Genetics Home|website=Genetics Home Reference|access-date=2016-11-16}}</ref> SNPs in [[Coding region|coding]] regions can cause [[Synonymous substitution|synonymous]], [[Missense mutation|missense]], and [[nonsense mutation]]s. SNPs have shown to be correlated with drug responses and risk of diseases such as [[Sickle-cell disease|sickle-cell anemia]], [[Alzheimer's disease]], cystic fibrosis, and more.<ref name="ApoE">{{Cite journal|last2=Caselli|first2=R. J.|last3=Reiman|first3=E. M.|last4=Valla|first4=J.|year=2012|title=APOE and neuroenergetics: An emerging paradigm in Alzheimer's disease|journal=Neurobiology of Aging|volume=34|issue=4|pages=1007–17|doi=10.1016/j.neurobiolaging.2012.10.011|pmc=3545040|pmid=23159550|last1=Wolf|first1=A. B.}}</ref>