A greater number of CAG repeats in the HT The gene – the genetic cause of Huntington’s disease – is linked to early disease onset and death, but is not an independent predictor of mortality in people with the neurodegenerative disease, study finds .
These results suggest that “non-genetic factors contribute to mortality status and warrant further investigation,” the researchers wrote.
No significant differences were found in gender, age at symptom onset, or functional and cognitive performance between living and deceased Huntington patients.
Larger studies are needed to confirm these findings and identify risk factors for mortality in people with Huntington’s disease – and in particular for female patients, who were found in this study to have the highest risk of death. raised.
The study, “Huntington’s disease: mortality and risk factors in an Australian cohortwas published in Journal of Neurological Sciences.
More CAG repeats linked to earlier onset of motor symptoms and death
Huntington’s disease is a progressive neurodegenerative disease characterized by symptoms such as uncontrolled movements, loss of cognitive function and psychiatric problems. Patients also experience progressive shrinkage, or atrophy, in a region of the brain known as the basal ganglia, which is responsible for coordinating movement.
The disease is caused by excessive repetitions of a part of DNA, called CAG triplets, in the HT embarrassed. Healthy people normally have between 10 and 35 CAG repeats, but those with Huntington’s disease can have 36 to 120 repeats. A higher number of CAG repeats has been linked to earlier onset of motor symptoms and younger age at death.
“However, when a potential for confusion [influencing] factors, such as cardiovascular disease, are taken into consideration, the association between CAG repeat duration and age at death was not found to be significant,” the researchers wrote.
Now, a team of researchers in Australia has assessed whether CAG repeat length, age of disease onset and basal ganglia atrophy are risk factors for mortality in people with Alzheimer’s disease. Huntington.
They retrospectively analyzed the medical records of 83 people (51 women and 32 men) diagnosed with Huntington’s disease who were admitted to the neuropsychiatry ward at the Royal Melbourne Hospital between 1992 and 2014. The records contained demographic, clinical, and brain imaging.
non-genetic factors contribute to mortality status and warrant further investigation
Patients had a risk of death almost six times higher than the general population
Cognitive function was assessed with the Mini-Mental State Examination and Neuropsychiatry Unit Cognitive Assessment Tool, while function was assessed with the Global Assessment of Functioning.
More than half of the patients (54.2%) were of Pacific/North West European origin and their median age was 41 years at onset of symptoms and 48 years at admission. The number of CAG repeats was available for 73 patients, who had a median of 44 repeats.
Functional and cognitive impairments were moderate and cerebral atrophy was present. Psychiatric/behavioural problems were the most common early symptoms (43.5% of patients), followed by motor symptoms (36.2%) and cognitive deficits (20.3%). More than half of the patients did not drink, smoke or report heart disease risk factors.
A total of 44 patients (53%) died during the period evaluated, at a median age of 59 years. Huntington’s disease was the leading cause of death (83.7%), with respiratory symptoms listed as a common secondary cause.
Median survival after symptom onset was 18.8 years. Huntington’s patients had a risk of death almost six times higher than the general population in Australia, with this risk being twice as high in women as in men (increased risk of 8.3 compared to 4.2).
Notably, patients aged 50 to 69 had a risk of death more than nine times higher than the general population.
While longer CAG repeat lengths were significantly associated with earlier disease onset and death, no significant differences were found in CAG repeat lengths and age of symptom onset between patients. living and dead.
The researchers also found no significant differences in gender, baseline symptom, functional ability, cognitive function, cardiovascular risk factors, alcohol consumption or smoking between these groups.
However, deceased patients had significantly more brain atrophy than living patients. Additionally, patients living with Huntington’s disease were significantly more likely to have a personal and family history of psychiatric problems and a family history of dementia than deceased patients.
“These findings may be explained by prior engagement with psychiatric and health services with ongoing support and care by individuals aware of their psychiatric and family history and that our sample was biased to being a neuropsychiatry service versus a neurology department,” the team wrote. .
Further statistical analyzes taking into account individual factors showed that CAG repeat length, age of disease onset, type of initial symptom, and cerebral atrophy were not predictors of mortality. in patients.
Epigenetics and lifestyle may more importantly affect disease progression
These results suggest that “although CAG repeat length is strongly associated with age of symptom onset, there may be other factors that more importantly affect symptom progression and death, such as ‘epigenetics and lifestyle factors,’ the team wrote.
Epigenetic factors refer to chemical modifications of DNA that influence the activity of genes without altering their underlying DNA sequence.
“The results of this study can be used to support health services and future research directions in this area,” the researchers wrote, adding that “the relatively long survival time underscores that maintaining quality of life while being symptomatic with HD [Huntington’s disease] is crucial.
The researchers pointed out some limitations of the study, including the small sample size and retrospective nature. They also noted that the participants were recruited from a specialist center and mostly had psychiatric or behavioral problems.
Further studies are needed to confirm these findings and provide “a thorough understanding of HD mortality risk factors beyond genetic findings,” the team wrote.
This may help Huntington’s patients “to adopt beneficial lifestyle changes to optimize their function and improve their quality of life while living with this disease,” the researchers concluded.
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