ALG9 and autosomal dominant polycystic kidney disease: Interestingly, monoallelic variants in ALG9 encoding the ER (endoplasmic reticulum) enzyme ɑ-1,2-mannosyltransferase were just recently identified in genetically unresolved, atypical ADPKD, including this very truncating variant, which had been found associated with mild bilateral PKD.15