ACOX1 and peroxisome biogenesis disorder: Several patients with DBP or ACOX1 deficiency or a ZSD have been reported with normal peroxisomal parameters in blood in whom diagnosis was only established or confirmed by studies in fibroblasts (Soorani-Lunsing et al 2005; Rosewich et al 2006; McMillan et al 2012; Lines et al 2014; Ratbi et al 2015).