Definition

A sequence of three nucleotides that is repeated a number of times in a row in a segment of DNA. A certain amount of variation in the number of trinucleotide repeats is common and usually does not cause disease in individuals. But too many copies of certain trinucleotide repeats in the DNA can affect the gene’s function, which could lead to certain genetic disorders. The number of trinucleotide repeats can change as the gene is passed from parent to child.