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Bone Fragility and Fracture Characteristics in Patients With Spinal and Bulbar Muscular Atrophy.
Takahiro Kawase1, Shinichiro Yamada1, Yoshiyuki Kishimoto1
1Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
European Journal of Neurology
|December 4, 2025
Summary
Spinal and bulbar muscular atrophy (SBMA) patients experience more fragility fractures, especially in cortical bone, due to decreased bone density and vitamin D deficiency. These fractures are linked to low bone turnover osteoporosis.
Area of Science:
- Neurology
- Endocrinology
- Metabolic Bone Disease
Background:
- Spinal and bulbar muscular atrophy (SBMA) is a hereditary neuromuscular disorder caused by androgen receptor gene mutations.
- SBMA is often associated with metabolic abnormalities, including potential impacts on bone health.
Purpose of the Study:
- To investigate the incidence of fragility fractures in SBMA patients.
- To explore the underlying mechanisms contributing to fractures in SBMA, focusing on bone metabolism and density.
Main Methods:
- A study comparing genetically confirmed SBMA patients with healthy controls (HC).
- Assessment included fracture history, motor function, bone metabolism markers, and bone mineral density (BMD) via dual-energy X-ray absorptiometry.
- Longitudinal BMD changes were analyzed in both groups.
Main Results:
- SBMA patients showed a higher incidence of fragility fractures, predominantly in cortical bone regions.
- Lower limb BMD was significantly reduced in SBMA patients and decreased progressively over time.
- Low bone turnover, vitamin D deficiency, and reduced BMD were identified as key factors associated with fractures in SBMA.
Conclusions:
- SBMA patients exhibit a high rate of fragility fractures, characterized by progressive BMD loss and low bone turnover.
- Vitamin D deficiency is prevalent and associated with increased fracture risk in SBMA.
- Reduced baseline BMD is a significant predictor of fragility fractures in individuals with SBMA.
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