MUC1 and autosomal dominant medullary cystic kidney disease with or without hyperuricemia: Considering this, we understand that ADTKD-MUC1 diagnosis is complex and that MUC1 pathogenic variants have been identified only recently by Kirby et al.5 because they lie in MUC1 VNTR region, which consists of many copies of a large repeat unit (60 base pairs) with a very high G-C content (>80%).