What are mutations (or genetic variants)?

The sequence of nucleotides (A, T, G, C) that makes up a gene can have variations:

  • One nucleotide may have been replaced by another (a G instead of an A, for example).
  • A part of the sequence may have been lost (deletion).
  • Other nucleotides may be added to the original gene sequence (insertion).

These variations or alterations in the sequence of a specific gene may be benign and have no consequences. Others may cause disease by generating a dysfunction in the protein they code for. These phenomena are known as mutations, and are the cause of genetic disorders.