Long repetitive sequences of C-A-G letters in the DNA code are associated with at least 12 genetic diseases, including Huntington’s disease (HD). A group of scientists in Massachusetts, USA, have recently developed a new genetic strategy to study how CAG repeats can lead to harmful proteins being made in cells, causing cells to become unhealthy. Their findings showed that expanded CAG repeats can interfere with a process called ‘splicing’, which chops up and organises genetic message molecules before they are turned into proteins.
CAG repetition
Our DNA is a genetic code that holds instructions for making thousands of different proteins, the molecular machines that run our cells. This code is made of four building blocks or ‘bases’: C, A, G, and T. DNA is arranged like a twisted ladder with two DNA strands bound together in a helix, each made of a string of bases. The bases on one DNA strand pair with bases on the opposite DNA strand to form the ‘rungs’ of the ladder.