Clinical feature: 

Definition: Medullary cystic kidney disease is an autosomal dominant disorder characterized by medullary cysts and progression end stage renal disease.

Pathogenesis: Pathogenetically two types can be distinguished MCKD1 and MCKD2. The gene that causes type 1 has yet to be identified. Type 2 is caused by mutations of the UMOD gene, which encodes Tamm-Horsfall protein. The pathogenetic mechanism behind the development of renal cysts and end stage renal disease remains to be discovered.

Clinical picture: Patients with medullary cystic kidney disease present in the third to fourth decades. Unintentionally, renal cysts or a slightly elevated serum creatitin are found in otherwise asymptomatic patients. End stage renal disease occurs in the fourth to seventh decade.
   The kidneys are of normal size or slightly smaller. Histopathology reveals thickening of the tubular basement membrane, tubular athrophy with cyst development at the corticomedullary junction, and interstitial cell infiltration with fibrosis.
   Both pathogenetic types show some clinical differences. MCKD2 occurs more frequent with hyperuricemia and gout and onset of end stage renal disease is earlier, with median age of 32 opposed to 62 in MCKD1.

Diagnostics: 

Differential: Medullary cystic kidney disease and nephronophthisis are indistinguishable by radiology or histopathology. Molecular genetic analysis may help.

Literature: 

Wolf MT et al. (2007) The Uromodulin C744G mutation causes MCKD2 and FJHN in children and adults and may be due to a possible founder effect.
Wolf MT et al. (2003) Mutations of the Uromodulin gene in MCKD type 2 patients cluster in exon 4, which encodes three EGF-like domains.
Hateboer N et al. (2001) Confirmation of a gene locus for medullary cystic kidney disease (MCKD2) on chromosome 16p12.
Kudo E et al. (2004) Familial juvenile hyperuricemic nephropathy: detection of mutations in the uromodulin gene in five Japanese families.
Auranen M et al. (2001) Further evidence for linkage of autosomal-dominant medullary cystic kidney disease on chromosome 1q21.
Stavrou C et al. (2002) Autosomal-dominant medullary cystic kidney disease type 1: clinical and molecular findings in six large Cypriot families.
Stavrou C et al. (2003) Outcome of kidney transplantation in autosomal dominant medullary cystic kidney disease type 1.