Department of Medical Physics and Biomedical Engineering, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Department of Chemistry, Sharif University of Technology, Tehran, Iran ; Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, Iran.
Bioimpacts. 2013;3(4):185-94. doi: 10.5681/bi.2013.037. Epub 2013 Dec 28.
Proximal spinal muscular atrophy (SMA) is one of the most significant neurodegenerative diseases amongst the autosomal-recessive genetic disorders which is caused by the absence of protein survival of motor neuron (SMN). A critical nucleotide difference in SMN2 compared to SMN1 gene leads to an inefficient protein. Hence, homozygous lack of SMN1 provides a progressive disease. Due to the high prevalence, up to now, several molecular diagnostic methods have been used which most of them are lengthy, expensive, and laborious.
In the present study, we exploited a gold nanoprobe-based method for semi-quantitative SMN1 gene dosage analysis compared to SMN2. The assay was done under hybridization process between Au nanoprobes and different ratios of SMN1/SMN2 amplicons.
UV-vis spectra indicated that after the salt addition, nanoprobes aggregated gradually and their peak shifted to longer wavelengths except in the stable target-nanoprobes hybridization. The results revealed that the homozygous genotype of SMN2 gene is distinguished from the heterozygous genotypes of SMN genes by the naked eye, whereas different ratio of heterozygous genotypes (SMN1/SMN2) are differentiated better from each other using peak analysis ratios.
The presented strategy is an alternative simple method for discrimination of homozygous deletion of SMN1 in less than 30 min. However, further evaluation of the assay using clinical samples is recommended prior to real-world use.
常染色体隐性遗传疾病中的近端脊髓性肌肉萎缩症（SMA）是最严重的神经退行性疾病之一，由运动神经元存活（SMN）蛋白缺失引起。SMN2 基因与 SMN1 基因相比存在关键核苷酸差异，导致蛋白效率低下。因此，SMN1 纯合缺失会导致进行性疾病。由于患病率高，迄今为止已经使用了几种分子诊断方法，其中大多数方法冗长、昂贵且费力。
在本研究中，我们利用基于金纳米探针的方法进行半定量 SMN1 基因剂量分析，与 SMN2 进行比较。该测定是在 Au 纳米探针与不同比例的 SMN1/SMN2 扩增子之间的杂交过程中进行的。
紫外-可见光谱表明，加入盐后，纳米探针逐渐聚集，峰位向长波长移动，除了在稳定的靶标-纳米探针杂交中。结果表明，SMN2 基因的纯合基因型可以通过肉眼与 SMN 基因的杂合基因型区分开来，而不同比例的杂合基因型（SMN1/SMN2）可以通过峰分析比值更好地区分彼此。
该策略是一种替代方法，可以在 30 分钟内简单区分 SMN1 的纯合缺失。然而，建议在实际应用之前，使用临床样本进一步评估该检测方法。
