English: Selection of notable mutations, ordered in a standard table of the genetic code of amino acids.

As can be seen, clinically important missense mutations generally change the properties of the coded amino acid residue between being basic, acidic, polar or nonpolar, while nonsense mutations result in a stop codon.

In the case of cancers, mutations cause aggravation of the conditions by impairing tumor suppressors or activating oncogenes.

Every U (uracil) in the mRNA corresponds to a T (thymine) in the original DNA. Therefore, mutations are often noted using T rather than U.

• Sickle-cell disease: GAG to GTG in the hemoglobin gene
• Huntington's disease: CAG insertions, which adds a string of glutamines to Huntingtin
• Friedreich's ataxia: In most cases, the mutant frataxin gene contains expanded GAA triplet repeats in the first intron;
• Dentatorubral-pallidoluysian atrophy (DRPLA), caused by an expansion of a CAG repeat encoding a polyglutamine tract in the atrophin-1 protein.
• Kennedy's disease, caused by expansion of a CAG repeat in the first exon of the androgen receptor gene.
• Fragile X Syndrome: CGG insertions on the X chromosome. Practically, however, these are not related to arginine, because the mutations are located in the 5' untranslated region.
• CTG in myotonic dystrophy.
• Spinocerebellar ataxia. Many types are caused by CAG repeats, see Wikipedia:Spinocerebellar ataxia#Treatment and prognosis for details.
  • Spinocerebellar ataxia: CTG
• β-thalassemia (β-globin gene)
  • C to U resulting in stop signal UAG
  • also UGG to UGA
• D1822V by GAC->GTC is the most common missense APC variant described to date in colorectal cancer.
• A49T (GCC to ACC), V63M and V89L are the most common missense substitutions in prostatic or in prostate cancer tissue.
• p.R50X is the most common nonsense mutation in myophosphorylase in McArdle's disease, the most common Glycogen storage disease