7. Expansion of Trinucleotide Repeats: An Increasing Threat
One of the key factors in Huntington’s disease is the expansion of trinucleotide repeats in the HTT gene. This process, where CAG repeats increase over time or generations, exacerbates the disease and can lead to earlier onset in subsequent generations.
This phenomenon, known as anticipation, is somewhat unique to diseases caused by trinucleotide repeat expansions. It means that children of affected parents can not only inherit the disease but may also experience symptoms earlier and progress more rapidly than their parents.
The expansion of CAG repeats is believed to occur during the copying of DNA when cells divide. Errors in this process can lead to additional repeats being added, especially in sperm cells. This is why anticipation is more frequently observed when the disease is passed from father to child. (7)
