A genetic adaptation that allows yaks to survive in oxygen-depleted environments high in the Tibetan mountains may offer new hope for patients suffering from multiple sclerosis, according to research published in the journal Neuron.
The discovery centers on a mutation of the Retsat gene, which researchers found not only protects but actively repairs the myelin sheath—the protective tissue layer surrounding nerve fibers in the brain and spinal cord. This finding represents a significant departure from current treatment approaches and could address conditions that currently have no cure.
Multiple sclerosis is a debilitating autoimmune disease affecting millions worldwide. The condition occurs when the immune system mistakenly attacks and destroys myelin, the insulating layer that protects nerve fibers and enables them to transmit signals throughout the body. As myelin deteriorates, patients experience progressive paralysis and neurological decline.
Professor Liang Zhang from Shanghai Jiao Tong University School of Medicine led the research team that investigated how animals living on the Tibetan Plateau—which averages 14,700 feet above sea level—maintain healthy brain function despite chronically low oxygen levels. Previous studies had identified the Retsat mutation in yaks and Tibetan antelopes, but its precise function remained unclear.
The research team exposed newborn mice to low-oxygen conditions equivalent to elevations above 13,000 feet for approximately one week. The results were striking. Mice carrying the Retsat mutation demonstrated significantly superior performance in learning, memory, and social behavior assessments compared to those with the standard gene version. Brain tissue analysis revealed substantially higher myelin levels surrounding nerve fibers in the mutation-carrying mice.
The team then examined whether the mutation could repair myelin damage similar to that observed in multiple sclerosis patients. Following induced injury, mice with the Retsat mutation exhibited myelin regeneration that was both faster and more complete than their counterparts. The injury sites also contained elevated numbers of mature oligodendrocytes—specialized cells responsible for myelin production.
Further investigation revealed the mechanism behind this enhanced repair capability. The Retsat mutation increased production of ATDR, a metabolite derived from vitamin A, in the brain. The mutation appeared to boost enzymatic activity that converts vitamin A into metabolites, which subsequently promotes oligodendrocyte production and maturation.
When researchers administered ATDR to mice with an MS-like condition, the animals showed decreased disease severity and improved motor function. This finding suggests a potential therapeutic pathway that differs fundamentally from existing treatments.
Current multiple sclerosis treatments focus exclusively on suppressing immune system activity to prevent further myelin damage. These approaches do not address myelin repair or regeneration. The Retsat pathway offers a complementary strategy that could actively restore damaged tissue.
Professor Zhang emphasized the broader implications of the research, noting that myelin damage occurs in several other conditions beyond multiple sclerosis. Insufficient oxygen during fetal brain development can damage the myelin layer, leading to cerebral palsy in newborns. Additionally, reduced blood flow to the brain associated with aging can compromise myelin integrity and contribute to vascular dementia.
The research team highlighted a significant advantage of this therapeutic approach: both Retsat and ATDR are naturally occurring biological molecules already present in the human body. This characteristic could potentially accelerate development and reduce safety concerns compared to entirely synthetic compounds.
Professor Zhang reflected on the broader significance of studying genetic adaptations across species. "Evolution is a great gift from nature, providing a rich diversity of genes that help organisms adapt to different environments," he stated. "There is still so much to learn from naturally occurring genetic adaptations."
While the findings represent a promising avenue for future therapies, the research remains in early stages. The study was conducted in mouse models, and considerable additional research will be necessary to determine whether similar therapeutic effects can be achieved in human patients. Clinical trials would be required to establish safety, optimal dosing, and efficacy in treating multiple sclerosis and related conditions.
The discovery underscores the value of comparative biology research and the potential for nature-inspired solutions to complex medical challenges. As scientists continue to investigate genetic adaptations across diverse species and environments, additional therapeutic pathways may emerge for conditions that currently lack effective treatments.