Congenital anomalies of the kidneys including renal dysplasia are the most common cause of renal failure in children. Sonographically renal dysplasia with cysts are frequently identified.
Hepatocyte nuclear factor-1ß (HNF1ß) is encoded by the TCF2 gene on chromosom 17q21.3. HNF1ß plays a role for the tissue-specific regulation of gene expression in various organs such as kidneys, liver, biliary ducts, pancreas and genital organs. In the kidneys HNF1ß is expressed in the proximal and distal tubuli and in the collecting duct.
Initially mutations in the HNF1ß-gene were described in association with the maturity onset diabetes of the young (MODY type 5) in 1997. It is characterized by an autosomal dominant, monogenic form of a noninsulin dependent diabetes mellitus. Moreover elevated liver enzymes, hyperuricaemia, genital tract malformations and renal disease were described (renal cysts and diabetes syndrome, RCAD). Additionally sometimes patients have a hypomagnesiaemia caused by hypermagnesiuria. It has recently been shown that in patients with isolated renal dysplasia with cysts HNF1ß-mutations can frequently been identified.
However limited data is available with respect to the clinical course, the progression of renal disease and the manifestation of extrarenal symptoms. Renal ultrasound in HNF1ß nephropathy is very variable, including unilateral and bilateral renal dysplasia with a different number and size of cysts. Some patients show a normal renal function, others develop an early renal failure. Also in one family there can be a great variability of symptoms.