A rare mutation may protect people with a familial form of early-onset Alzheimer’s disease from developing it. The mutation, located in the gene APOE3, hampers how its protein binds with sugars that play a role in the disease. Targeting this process might yield novel therapies, the researchers say (Nat. Med. 2019, DOI: 10.1038/s41591-019-0611-3).
Researchers discovered the apparently protective mutation when studying people within an extended family in Medellín, Columbia, who carry a mutation in a different gene, called presenilin 1 (PSEN1). About half of those who carry the PSEN1 mutation develop early signs of the disease by their mid-40s and dementia by around age 50.
During their research, scientists encountered one woman who stood out: although she carried the PSEN1 mutation and was in her 70s, she had only mild cognitive impairment. What’s more, the woman’s brain also had high levels of clumped proteins called amyloid plaques, a characteristic sign of Alzheimer’s. Though she had more amyloid plaques than people with the PSEN1 mutation who develop the disease in their 40s, she had few symptoms.