Furthermore, the characteristic profiles identified in PED fibroblasts resulted in specific sets of ratios for fibroblasts from peroxisomal β-oxidation disorders with the affected enzymes located inside the peroxisome (ACOX1- and DBP deficiency) when compared to disorders with the affected proteins outside the peroxisome (ALD, ACBD5 deficiency). Here, ACOX1 is linked to X-linked adrenoleukodystrophy.