Although clinically informative, both studies lacked sufficient statistical power to further extend the transcription profiling to a biomarker applicable to all AOA2 patients (Fogel et al. 2014) or all ALS4 patients (Hadjinicolaou et al. 2021) due to limited patient numbers, low sensitivity, and limited resolution of the transcriptional data. This evidence concerns the gene SETX and amyotrophic lateral sclerosis type 4.