FIS1 and Zellweger syndrome: The expression level of FIS1 mRNA analyzed by qPCR was significant reduced (p = 0.015) in PEX26 deficient fibroblast of a patient with the severe phenotype of Zellweger syndrome (GM17398) (Weller et al., 2005) as compared to a healthy fibroblast cell line (Figure 6A).