BBX and Marinesco-Sjogren syndrome: In order to elucidate the role of NFIX mutations in MSS, we initially studied their effects on GFAP and BBX expression in fibroblast cell lines obtained from 5 MSS patients, and then utilized these fibroblasts and mouse embryonic fibroblasts (MEFs) derived from wild-type (Nfix+/+) mice, heterozygous (Nfix+/Del2, Nfix+/Del24 and Nfix+/Del140) and homozygous (NfixDel2/Del2, NfixDel24/Del24 and NfixDel140/Del140) mutant mouse models11 in hypothesis-free approaches of RNA sequencing and proteomic analyses (Figure S1).