Triplet expansions

In genetics, triplets are described as a type of mutation characterized by repeats of three nucleotides. Triplet expansions, or trinucleotide repeat expansion, occur when more triplets are present in a mutated gene than in the normal gene. As diseases related to triplets are inherited, the number of triplets continues to increase. Diseases including Fragile X Syndrome, Spinal muscular atrophy, and Huntington's disease are caused by triple repeats in genes.