UMOD and autosomal dominant medullary cystic kidney disease with or without hyperuricemia: ADTKD-UMOD is caused by amino acid changing mutations of UMOD which lead to a pronounced protein maturation and secretion defect of both mutated and native UMOD, massive accumulation of immature UMOD in the enlarged ER of TAL cells and strongly reduced urinary UMOD excretion1, 6.