Uromodulin (UMOD) storage disease or UMOD-associated kidney disease is autosomal dominant disease developed from mutation of uromodulin (Tamm-Horsfall protein). Patients present with chronic renal insufficiency and gout. Spectrum of disease includes familial juvenile hyperuricemic nephropathy (FJHN), medullary cystic kidney disease type 2 (MCKD2) and glomerulocystic kidney disease.
Focal tubular atrophy and interstitial fibrosis with intracytoplasmic inclusions in distal tubules and/or thick ascending limbs of the Henle are seen in kidney biopsy. Ultrastructurally, the inclusions are identified as hyperplastic endoplasmic reticulum (ER) containing UMOD. Immunostaining for UMOD reveals positivity of UMOD aggregates within cells whereas normal distal tubules show diffuse cytoplasmic and apical staining.
Although the histopathologic finding is characteristic, genetic test is required for definite diagnosis.
https://doi.org/10.1038/sj.ki.5002679
