This process is highly regulated by an ER-located transmembrane receptor called protein kinase RNA-like endoplasmic reticulum kinase (PERK), as it has recently emerged that an increase of VLCFA, especially C26:0, induces ER stress in human ALD fibroblasts with a subsequent activation of the PERK pathway [219]. This evidence concerns the gene EIF2AK3 and X-linked adrenoleukodystrophy.