It is relevant to compare these biochemical analyses with those of iPSCs derived from the skin fibroblasts from individuals with X-linked adrenoleukodystrophy (X-ALD) [20, 67], a complex neurological disorder caused by mutations in the ABCD1 gene that encodes a peroxisome membrane protein [68–70]. Here, ABCD1 is linked to adrenoleukodystrophy.