A case study has reported an association between an exact genetic mutation and Huntington’s disease prognosis, which may help tailor treatments at early stages of the disease.
Huntington’s disease is linked to a mutation in the HTT gene that codes for the huntingtin protein. An accumulation of the abnormal form of the protein is what plays a role in the pathology of the disease. The genetic code, or DNA sequence, provides instructions for a series of amino acids, the building blocks of proteins. A mutation in the genetic code sequence results in the production of an abnormal form of a protein.
In the huntingtin protein, the presence of a triplet code (in this case, CAG) at the DNA level results in an abnormal protein containing repeats of an amino acid known as glutamine. Current evidence suggests that the number of CAG repeats is associated with disease prognosis.
A recent case report titled “Major Neurocognitive Disorder of Rapid Progression in Huntington’s Disease Associated with Triplet Repeat CAG,” published in MOJ Gerontology and Geriatric, helps increase our knowledge of how the CAG repeats can influence cognitive outcomes in patients.
The report describes the case of a 53-year-old woman who has been diagnosed with Huntington’s disease through genetic testing.
Her DNA had 42 CAG repeats. She was assessed using several neuropsychological tests and the results revealed that she had many difficulties in several areas, including working memory, organization in behavior planning, slow information processing, and learning new information.
Although she had preserved basic daily activities, instrumental activities were affected. Cognitive tests indicated she had moderate to severe cognitive deterioration, which is considered a risk for developing dementia.
The researchers highlight the fact that the patient had reached such a state within two and a half years of the onset of symptoms means that the 42 CAG repeats played a role in her relatively fast disease progression.
They do point out though, that since typical progression takes about 10 to 20 years, there is a possibility that the patient might have a secondary genetic factor that might have contributed to this rapid progress. Another possible contributing factor could be the patient’s chronic alcohol and tobacco consumption.
One of the advantages of such studies linking genetic sequences to disease prognosis is that they help establish with better precision the prognosis of the disease, which may help in providing a timely treatment allowing the patient to be as functional as possible.