The seeding amplification assay (SAA) has recently emerged as a valuable tool for detecting α-synuclein (αSyn) aggregates in various clinically accessible biospecimens. Despite its efficiency and specificity, optimal tissue-specific conditions for distinguishing Parkinson’s disease (PD) from non-PD outside the brain remain underexplored. This study systematically evaluated 150 reaction conditions to identify the one with the highest discriminatory potential between PD and non-synucleinopathy controls using skin samples, resulting in a modified SAA. The streamlined SAA achieved an overall sensitivity of 92.46% and specificity of 93.33% on biopsy skin samples from 332 PD patients and 285 controls within 24 h. Inter-laboratory reproducibility demonstrated a Cohen’s kappa value of 0.87 (95% CI 0.69–1.00), indicating nearly perfect agreement. Additionally, αSyn seeds in the skin were stable at −80 °C but were vulnerable to short-term exposure to non-ultra-low temperatures and grinding. This study thoroughly investigated procedures for sample preprocessing, seed amplification, and storage, introducing a well-structured experimental framework for PD diagnosis using skin samples.

播种扩增测定 (SAA) 最近已成为检测各种临床可获取的生物样本中 α-突触核蛋白 (αSyn) 聚集体的有价值的工具。尽管具有高效性和特异性，但用于区分帕金森病 (PD) 与大脑外非 PD 的最佳组织特异性条件仍未得到充分探索。这项研究使用皮肤样本系统地评估了 150 种反应条件，以确定 PD 和非突触核蛋白病对照之间最具区分潜力的反应条件，从而产生了修改后的 SAA。简化的 SAA 在 24 小时内对 332 名 PD 患者和 285 名对照者的活检皮肤样本实现了 92.46% 的总体敏感性和 93.33% 的特异性。实验室间重现性表明 Cohen kappa 值为 0.87（95% CI 0.69–1.00），表明几乎完全一致。此外，皮肤中的αSyn种子在-80°C下稳定，但容易受到短期暴露于非超低温和研磨的影响。这项研究彻底研究了样本预处理、种子扩增和储存的程序，引入了一个结构良好的使用皮肤样本进行 PD 诊断的实验框架。