Different types of genetic changes by which they can alter phenotype
Types of Genetic Changes and Common Mechanisms by Which They Lead to Phenotypic Alterations
| Chromosome abnormalities | Changes in the number or structure of chromosomes |
| DNA deletions | Deletions of DNA sequences |
| DNA insertions | Insertions of DNA sequences |
| Single Base Changes | |
| Missense | Single base substitutions leading to a change in amino acid sequence |
| Nonsense | Single base substitution leading to replacement of an amino acid codon with a stop codon |
| Splice site | Destruction or creation of a signal regulating the splicing of exons and introns |
| Synonymous | Substitution of one base for another that does not change the amino acid sequence of a protein coding gene. Some synonymous changes affect transcription, mRNA splicing/transport, or translation, leading to phenotypic abnormalities |
| Frameshift changes | Sequence variants (e.g., deletion, insertion, or splice site) leading to a change in the normal open reading frame of a protein coding gene |
| Regulatory changes | Sequence changes altering the level of gene expression |
| DNA expansion | Repeat sequences (e.g., triplet repeat disorders) that can change in size over time |
| Silent DNA changes | DNA changes occurring in either noncoding or coding regions of a gene that do not cause phenotypic changes |
