While the expression of 7SL has often been shown to be decreased, as has been seen in blood samples from individuals with the striatal form of POLR3-related leukodystrophy and fibroblasts from individuals with biallelic pathogenic POLR3K variants, this finding is not consistent, as in fibroblasts from patients with a typical disease course, 7SL was unaffected (Shimojima et al., 2014; Azmanov et al., 2016; Dorboz et al., 2018; Choquet et al., 2019). This evidence concerns the gene POLR3K and leukodystrophy.