Single Gene Mutation Shields Brains From Alzheimer’s – and Scientists Now Know Why

A single gene mutation offers remarkable protection against early-onset Alzheimer’s disease, and scientists are now beginning to understand why. The key lies in a protein called reelin, which appears to enhance the brain’s ability to clear the toxic buildup of amyloid plaques and tau tangles characteristic of the disease. New research suggests that this mutation doesn’t just slow the progression of Alzheimer’s – in some cases, it appears to negate the effects of a gene that almost guarantees the condition develops in mid-life.

A Colombian Family’s Resilience

For decades, a large family in the lush valleys near Medellín, Colombia, has been the focus of intense study due to a rare genetic mutation in the PSEN1 gene. This mutation causes a particularly aggressive form of early-onset Alzheimer’s, typically leading to memory loss in individuals in their 40s. However, within this family, one man defied the odds. He carried the PSEN1 mutation but remained cognitively healthy well into his 60s. This neurological anomaly sparked a search for a protective factor, ultimately leading to the discovery of another mutation, dubbed COLBOS, named after the research centers in Colombia and Boston involved in its characterization.

Neurologist Dr. Francisco Lopera, who grew up in the affected region, dedicated years to mapping the prevalence of this genetic form of Alzheimer’s. His work was instrumental in identifying the families at risk and ultimately led to the discovery of the COLBOS mutation just before his death in 2024. His co-authored paper in The Lancet detailed the case of this resilient individual, offering a crucial clue in the fight against Alzheimer’s.

How Reelin Strengthens the Brain’s Defenses

Initial research identified that the COLBOS mutation altered the function of reelin, a protein vital for brain development and synaptic plasticity – the brain’s ability to form new connections. Reelin is known to prevent the activation of the tau protein and inhibit the formation of amyloid plaques. However, the precise mechanism by which COLBOS conferred protection remained unclear. Recent research published in December 2025 in the Journal of the American Chemical Society, led by molecular biologist Chunyu Wang at the Rensselaer Polytechnic Institute, has shed light on this process.

Wang’s team used surface plasmon resonance to map how the COLBOS mutation affects reelin’s interaction with heparan sulfate, a sugar molecule found on the surface of cells throughout the body, including neurons. The study revealed that COLBOS strengthens the bond between reelin and heparan sulfate. This increased binding affinity allows reelin to accumulate on the surface of neurons, maximizing its protective effects. When localized to the cell surface, reelin more effectively combats key Alzheimer’s processes, such as the phosphorylation of tau, a process that leads to the formation of toxic tangles.

Neuroscientist Dr. Joachim Herz, at the University of Texas Southwestern Medical Center, who was not involved in the new research, remarked on the surprising degree of protection offered by the COLBOS mutation. He told Live Science, “I would never have expected that it would be so protective that it actually negates the effect of a dominant early onset Alzheimer’s disease mutation.”

The Role of Cellular “Shredders”

While the COLBOS mutation offers significant protection, it doesn’t entirely prevent the onset of Alzheimer’s. Dr. Herz’s research suggests that individuals with the PSEN1 mutation experience malfunctions in organelles called endolysosomal compartments – essentially the cell’s waste disposal system. These compartments are responsible for breaking down and removing toxic proteins like tau and amyloid. The COLBOS mutation appears to enhance the efficiency of this process, but as the brain ages, the defects in these “shredders” become increasingly hard to overcome.

This suggests that bolstering the function of these cellular waste disposal systems could be a promising therapeutic strategy, even for individuals without the rare COLBOS mutation. Recent research, as reported by NPR, highlights the importance of reelin throughout life, not just in protecting against Alzheimer’s, but too in maintaining overall brain health and resilience to aging.

Implications for Future Therapies

The discovery of COLBOS and its impact on reelin function opens new avenues for Alzheimer’s therapies. Wang’s team is exploring the development of a gene therapy designed to enhance reelin signaling, potentially boosting its protective effects even in individuals with lower levels of the protein. The goal is to improve reelin’s efficiency at the cell surface, maximizing its ability to prevent tau phosphorylation and amyloid plaque formation.

While current Alzheimer’s drugs offer modest benefits, extending independent living by only a few years, Wang believes that a therapy capable of mimicking the effects of the COLBOS mutation could represent a significant breakthrough. Even delaying the onset of Alzheimer’s by a substantial margin would have a profound impact on the lives of millions. Research indicates that reelin-producing neurons are among the first to be lost in Alzheimer’s disease, suggesting that preserving or restoring these neurons could be a critical step in preventing cognitive decline.

Looking Ahead: Researchers are now focused on understanding how to safely and effectively enhance reelin signaling in the brain. Clinical trials will be necessary to assess the potential of gene therapies and other interventions aimed at boosting reelin function. The ultimate goal is to develop a treatment that can not only slow the progression of Alzheimer’s disease but potentially prevent it altogether.