Triplet expansion is caused by slippage during DNA replication or during DNA repair synthesis. Because the tandem repeats have identical sequence to one another, base pairing between two DNA strands can take place at multiple points along the sequence. This may lead to the formation of 'loop out' structures during DNA replication or DNA repair synthesis. This may lead to repeated copying of the repeated sequence, expanding the number of repeats. Additional mechanisms involving hybrid RNA:DNA intermediates have been proposed.
Trinucleotide repeat disorder
Lysosomal storage disease
Ribosomopathy
Lipid storage disorder
Trinucleotide repeat expansion
Creatine transporter defect
Cerebral creatine deficiency
Peroxisomal disorder