In family 3, we identified a pathogenic heterozygous splice-site PEX1 variant, c.1239+1G>T,23 also previously reported in individuals with a severe peroxisome-biogenesis disorder (PBD) and in trans with an ultra-rare missense variant. This evidence concerns the gene PEX1 and Peroxisome biogenesis disorder-Zellweger syndrome spectrum.