Neurodegenerative diseases affect millions of people worldwide, and for them there is no cure, only treatments that reduce symptoms. But researchers have discovered the gene that protects against Alzheimer’s and Parkinson’s, and only good things could happen from here, scientists believe.
Neurodegenerative diseases, such as Alzheimer’s or Parkinson’s, have a major impact on both affected individuals and their family members. Worldwide, there are more than 55 million people living with dementia, and those with Alzheimer’s account for approximately 60-70% of dementia cases, while Parkinson’s disease affected 8.5 million people in 2019.
A major study has revealed that a variation in a gene involved in an immune response protects those who carry it against Alzheimer’s and Parkinson’s diseases.
Known as DR4 or the allele, the variant is part of a family of genes that normally help our immune system identify and destroy foreign invaders such as bacteria and viruses.
“In a previous study, we found that carrying the DR4 allele seems to protect against Parkinson’s disease,” says psychiatrist and geneticist Emmanual Mignot from Stanford University in the US, the institution that led the study.
But Alzheimer’s and Parkinson’s are distinct conditions, with different pathological biomarkers in the brain—Lewy bodies for Parkinson’s and abnormal tangles of the tau protein in Alzheimer’s disease.
Thus, the discovery of DR4 as a common factor was surprising.
“The fact that this protective factor for Parkinson’s ended up having the same protective effect for Alzheimer’s amazes me. The night after I found out, I couldn’t sleep,” says Mignot.
The scientists collected medical and genetic data from dozens of data banks around the world, which gave them a diverse data set that included participants from Europe, Asia, Latin America and African America.
Comparing data from 176,000 Parkinson’s or Alzheimer’s patients with just under 2 million control cases found that those who carried the DR4 variant were significantly less likely to suffer from either disease – in fact, a more than 10% less likely.
The researchers then studied data from 7,000 autopsied brains affected by Alzheimer’s, finding that those with the DR4 gene mutation had a later onset of symptoms and fewer neurofibrillary tangles, which correlate with the severity of the disease.
According to them, a fragment of Alzheimer’s disease biomarkers, acetylated PHF6 (α-PHF6), is essential for the formation of these clusters.
Laboratory experiments have shown that DR4 proteins bind strongly to this fragment.
Because of this strong connection, the immune system recognizes the clumps typical of Alzheimer’s disease as foreign and eliminates them, just as it would a virus or bacteria.
Even though these entanglements are not a mechanism for Parkinson’s, carrying DR4 has been correlated with later-onset symptoms in this disease as well. Another win for DR4.
“This immune response would protect against Alzheimer’s disease, Parkinson’s disease and neurodegeneration,” the researchers note Science Alert.
It must be remembered that none of these neurodegenerative diseases has a cure, and current treatments are aimed at reducing the symptoms, respectively improving the life and quality of life of these patients.
2023-10-29 22:02:00
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