A<unk> , also known as a triplet<unk><unk> , is the DNA mutation responsible for causing any type of disorder categorized as a trinucleotide<unk>  disorder. These are labelled in dynamical genetics as dynamic mutations. Triplet<unk>  is caused by slippage during DNA replication, also known as "copy choice" DNA replication. Due to the<unk> itive nature of the DNA sequence in these regions, 'loop out' structures may form during DNA replication while maintaining complementary base pairing between the parent strand and daughter strand being synthesized. If the loop out structure is formed from the sequence on the daughter strand this will result in an increase in the number of<unk> s. However, if the loop out structure is formed on the parent strand, a decrease in the number of<unk> s occurs. It appears that<unk>  of these<unk> s is more common than reduction. Generally, the larger the<unk>  the more likely they are to cause disease or increase the severity of disease. Other proposed mechanisms for<unk>  and reduction involve the interaction of RNA and DNA molecules. In addition to occurring during DNA replication,<unk>  can also occur during DNA repair. When a DNA trinucleotide<unk>  sequence is damaged, it may be repaired by processes such as homologous recombination, non-homologous end joining, mismatch repair or base excision repair. Each of these processes involves a DNA synthesis step in which strand slippage might occur leading to<unk> . The number of trinucleotide<unk> s appears to predict the progression, severity, and age of onset of Huntington's disease and similar trinucleotide<unk>  disorders. Other human diseases in which triplet<unk><unk>  occurs are fragile X syndrome, several spinocerebellar ataxias, myotonic dystrophy and Friedreich's ataxia.
Trinucleotide repeat expansion
Trinucleotide repeat disorder
Copy number variation
Ribosomopathy
Postzygotic mutation
Chromosomal translocation
Mitochondrial toxicity
Creatine transporter defect