what do mutations cause changes in
Altering nucleotide sequences most often results in nonfunctioning proteins. Mutations cause changes in the genetic code that lead to genetic variation and the potential to develop disease. Gene mutations can be generally categorized into two types: point mutations and base-pair insertions or deletions. Point mutations are the most common type of gene mutation. Also called a base-pair substitution, this type of mutation changes a single nucleotide base pair.