Huntington's Disease Causes And Diagnosis

New Mutation

In rare cases, a new mutation may form, resulting in a patient with Huntington's disease who did not inherit the disease from either parent. This is known as a de novo mutation of the HTT gene, which is the gene that gives the instructions for making the protein huntingtin. Scientists understand the mutation of the HTT gene causes Huntington's. Within the HTT gene, there is a DNA segment called the CAG trinucleotide repeat, which consists of three parts that repeat multiple times. A normal CAG repeats ten to thirty-five times. In Huntington's patients, the CAG repeats thirty-five to 120 times. Individuals with thirty-five to thirty-nine CAG repeats may or may not develop Huntington's, while those with over forty repeats typically always develop the disease. In addition, data shows patients with higher CAG repeats tend to have symptoms earlier in life that ultimately become more severe. Data suggests when Huntington's is passed down through generations, individuals tend to have higher CAG repeats.

Continue to learn about the risk factors of Huntington's next.