Nagoya University Researchers Identify Infantile Testosterone Spike as Primary Trigger for Adult Muscle Wasting Disease

Nagoya University researchers discover that a testosterone surge at birth triggers SBMA, offering a new window for early preventative gene therapy.

By: AXL Media

Published: Mar 27, 2026, 6:43 AM EDT

Source: Information for this report was sourced from Nagoya University

The Neonatal Origins of Adult Neurodegeneration

Scientific understanding of Spinal and Bulbar Muscular Atrophy, a debilitating inherited condition, has been fundamentally reshaped by new evidence identifying birth as the disease's true starting point. Researchers at Nagoya University have demonstrated that the progressive muscle wasting traditionally diagnosed in men during their forties is actually set in motion by a brief physiological spike in testosterone occurring just days after delivery. This "mini-puberty" phase, which lasts approximately six months in humans, triggers the overactivation of motor neurons in those carrying the specific genetic mutation, creating a destructive trajectory that remains dormant for decades.

Tracking the Mutant Protein During Mini-Puberty

The study, published in Nature Communications, focused on the behavior of the mutant androgen receptor protein, which requires testosterone to enter the nucleus of nerve cells and initiate damage. By monitoring newborn mice, the team confirmed that the accumulation of this toxic protein begins within the first twenty-four hours of life in males. Conversely, female mice with the same mutation showed no such accumulation, confirming that the early hormonal surge is the mandatory catalyst for the disease. According to lead author Tomoki Hirunagi, this hormonal interaction represents the earliest possible moment of disease onset.

Cellular Overactivity and Human Correlation

Beyond protein accumulation, the researchers identified a significant abnormality in the genes responsible for activating nerve cells, specifically glutamate receptors. These receptors became dangerously overactive during the first week of life in the presence of the mutation. To validate these findings for human application, the team grew motor neurons in a laboratory setting using cells from actual patients. The results mirrored the animal models, suggesting that the human disease process likely follows the same early-life pattern of neuronal overexcitation and subsequent breakdown.