Spinal and bulbar muscular atrophy (SBMA) is a rare neurodegenerative disorder caused by polyglutamine expansion in the androgen receptor. Before the disorder was found to be androgen-dependent, many patients with SBMA were treated with testosterone. Chevalier-Larsen and Merry now use a mouse model of SBMA to test whether androgen treatment might have exacerbated the disease in these patients. Surprisingly, testosterone treatment did not have any effect on the mice, suggesting that patients that received this treatment did not suffer ill effects, and that the pathological mechanism of SBMA saturates at near-endogenous hormone levels. Page 141

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