Types of DNA Changes

Your genome sequence is different from everyone else’s, unless you have an identical twin. These differences, or variants, arise from changes, or mutations, to the DNA. Most of the variants in your genome are inherited, though a small number of new ones arise in each generation. Some DNA changes affect the specific instructions in a gene. It is not always possible to predict whether a DNA change is important.

There are multiple types of DNA changes, including:

• The substitution of one single DNA base letter with another (Substitution)
• The addition or removal of one or more DNA base letters (Insertion/Deletion)
• The inversion of two or more DNA base letters (Inversion)
• The duplication of one or more DNA base letters (Duplication)
• The movement of several DNA bases from one location to another in the genome (Translocation)

When a particular substitution change occurs in more than 1% of the population, it is considered a common variant. These are also referred to as Single Nucleotide Polymorphisms (SNPs).

There are also sections of DNA bases in our genomes which are commonly copied many times over. The number of copies may vary from person to person. These changes are called Copy Number Variations (CNVs). Again, these may, or may not, be important.