Editing Stop codon (section)

== Mutations and disease ==
=== Nonsense ===
[[Nonsense mutations]] are changes in DNA sequence that introduce a premature stop codon, causing any resulting protein to be abnormally shortened. This often causes a loss of function in the protein, as critical parts of the amino acid chain are no longer assembled. Because of this terminology, stop codons have also been referred to as '''nonsense codons'''.

=== Nonstop ===
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{{anchor|nonstop mutation}}

A '''nonstop mutation''', also called a '''stop-loss variant''', is a [[point mutation]] that occurs within a stop codon. Nonstop mutations cause the continued translation of an [[mRNA]] strand into what should be an untranslated region. Most [[polypeptides]] resulting from a gene with a nonstop mutation lose their function due to their extreme length and the impact on normal folding. Nonstop mutations differ from [[nonsense mutations]] in that they do not create a stop codon but, instead, delete one. Nonstop mutations also differ from [[missense mutation]]s, which are point mutations where a single nucleotide is changed to cause replacement by a different [[amino acid]]. Nonstop mutations have been linked with many inherited diseases including [[endocrine]] disorders,<ref>{{cite journal |title=A novel nonstop mutation in the stop codon and a novel missense mutation in the type II 3beta-hydroxysteroid dehydrogenase (3beta-HSD) gene causing, respectively, nonclassic and classic 3beta-HSD deficiency congenital adrenal hyperplasia |author=Pang S. |author2= Wang W. |year=2002 |journal=J Clin Endocrinol Metab |volume=87 |issue=6 |pages=2556–63 |doi=10.1210/jcem.87.6.8559 |pmid=12050213 |display-authors=etal|doi-access=free }}</ref> eye disease,<ref>{{cite journal |author=Doucette, L. |title=A novel, non-stop mutation in ''FOXE3'' causes an autosomal dominant form of variable anterior segment dysgenesis including Peters anomaly |journal=European Journal of Human Genetics |volume=19 |issue=3 |year=2011 |pages=293–9 |doi=10.1038/ejhg.2010.210|display-authors=etal |pmid=21150893 |pmc=3062009}}</ref> and [[neurodevelopmental disorder]]s.<ref>{{cite journal |author=Torres-Torronteras, J. |author2=Rodriguez-Palmero, A. |year=2011 |title=A novel nonstop mutation in TYMP does not induce nonstop mRNA decay in a MNGIE patient with severe neuropathy |journal=Hum. Mutat. |volume=32 |issue=4 |pages=E2061–E2068 |doi=10.1002/humu.21447|display-authors=etal |pmid=21412940|s2cid=24446773 |url=https://hal.archives-ouvertes.fr/hal-00613761/file/PEER_stage2_10.1002%252Fhumu.21447.pdf }}</ref><ref name="STXBP1">{{Cite journal |last1=Spaull |first1=R |last2=Steel |first2=D |last3=Barwick |first3=K |last4=Prabhakar |first4=P |last5=Wakeling |first5=E |last6=Kurian |first6=MA |date=2022-07-23 |title= STXBP1 Stop-Loss Mutation Associated with Complex Early Onset Movement Disorder without Epilepsy |journal=Movement Disorders Clinical Practice |volume=9 |issue=6 |pages=837–840 |doi=10.1002/mdc3.13509 |pmid=35937496 |pmc=9346254 }}</ref>