Triplet repeats are sequences of three nucleotides in DNA that are repeated multiple times. These repeats can occur in various genes and are often associated with certain genetic disorders. When the number of repeats exceeds a normal range, it can lead to unstable gene expression and contribute to diseases such as Huntington's disease and Fragile X syndrome. The mechanism behind triplet repeats involves the DNA replication process, where the repeated sequences can expand or contract. This instability can result in the production of abnormal proteins, affecting cellular function and leading to the symptoms of the associated disorders. Understanding triplet repeats is crucial for genetic research and potential therapies.