Spinal muscular atrophy (SMA) is a genetic disease, and molecular test is available using whole blood as sample. In muscle biopsy, SMA shows denervation and reinnervation, demonstrated easily on histochemical stains of frozen sections. Immunohistochemistry of paraffin sections is not very useful, except perhaps fast myosin stain to highlight type 2 myofibers.

 马老师说：

脊髓型肌萎缩 (Spinal muscular atrophy ，SMA) 是一种遗传性疾病，可采用全血做分子检测来诊断。若肌肉活检，SMA 显示有去神经支配和神经修复性改变，用冷冻切片做组织化学染色可见这种改变。石蜡切片免疫组织化学染色除了快肌球蛋白染色可以凸显2型肌纤维之外，（对诊断）不是很有用。

 谢谢马老师和海上明月。