To identify new tRNA targets of human FTSJ1, we compared the Nm modification profiles of positions 32 and 34 for all detectable tRNA species in human lymphoblastoid cell lines (LCLs) obtained from control individuals (n = 4) versus LCLs obtained from individuals with XLID harbouring loss of function and pathogenic variants in FTSJ1 (n = 5, from four unrelated families) (Table 1). This evidence concerns the gene FTSJ1 and cask-related x-linked intellectual disability.