2023-05-16 17:04:52
A man, although genetically predisposed, resisted Alzheimer’s disease thanks to a previously unknown genetic variant which preserved him from the symptoms of the disease.
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The doctors of Massachusetts General Hospital (Mass General ou MGH) in the United States have discovered a new genetic variant that protects against Alzheimer’s disease. ” The genetic variant we have identified shows a mechanism that engenders resilience and extreme protection against the symptoms of Alzheimer’s disease », comment Joseph F. Arboleda-Velasquez, scientist who participated in the study published in Nature Medicine.
The discovery is all the more fascinating because it was made in a 67-year-old man with a genetic predisposition for Alzheimer’s disease. He and other members of his family carry the PSEN1-E280A mutation. People affected by it suffer from the first signs of dementia around the age of 40-50 and die of complications related to their cognitive decline around the age of 60. But this patient thwarted all predictions! He was not diagnosed with moderate dementia until age 72 and died of lung disease at age 74.
A new protective gene for Alzheimer’s
Mass Gen doctors performed post-mortem analyzes and identified a rare and previously unknown genetic variant that would have offset the negative effects of the PSEN1-E280A mutation. It was christened Reelin-COLBOS. Reelin-COLBOS affects the gene for reelin, a “cousin” protein of APOE3. Both bind to the same receptor but cause opposite effects: reelin decreases the phosphorylation of tau proteins, responsible for pathological clusters in the brain of Alzheimer’s patients, while APOE3 promotes the phosphorylation of tau proteins.
Images from a brain scan taken just before the patient’s death reveal a large amount of amyloid plaques and tau protein aggregates, but the entorhinal cortex, which plays a predominant role in memory, seems to be spared. ” This case indicates that the entorhinal cortex may represent a critical small target for protection against dementia “, explains Yakeel T. Quiroz, neuroscientist and director of this research.
Doctors cannot be 100% sure that the protective effect against Alzheimer’s is 100% due to the Reelin-COLBOS variant, other genetic variants could have contributed. But preclinical studies in mice suggest that Reelin-COLBOS is strongly involved. Treatments that target this gene and its action are being studied.
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