SIL1 and Marinesco-Sjogren syndrome: Given that mitochondria display a considerable vulnerability in the etiology of MSS (13, 18–20), WST-1 assay has been performed to investigate mitochondrial activity in our MSS in vitro models and results suggest a benign character of the p.R92W and p.K132Q amino acid changes in SIL1 whereas the pathogenic character of the p.G312R and p.L457P missense mutants could be confirmed.