PEX26 and peroxisomal disease: Heimler syndrome is a peroxisome disorder caused by biallelic variants in PEX1, PEX6, and PEX26. Proband 46 and several published cases with suspected USH presented biallelic mutations in PEX1 and PEX26 (Neuhaus et al. 2017; Diñeiro et al. 2020).