- Substitutions (base is replaced by one of the other three bases)
- transition exchanges a purine for a purine (A ↔ G) or a pyrimidine for a pyrimidine, (C ↔ T).
- transversion exchanges a purine for a pyrimidine or a pyrimidine for a purine (C/T ↔ A/G).
- Insertions add one or more extra nucleotides into the DNA.
- Deletions remove one or more nucleotides from the DNA.
Large-scale mutations in chromosomal structure
- Duplications leading to multiple copies of all chromosomal regions
- Deletions of large chromosomal regions, leading to loss of the genes within those regions.
- Translocations: parts of nonhomologous chromosomes change places
- Chromosomal inversions: reversing the orientation of a chromosomal segment.