Recent reports on the discovery of mutations of the uromodulin (UMOD) gene in families with FJHN encouraged us to screen UMOD mutations in Japanese families with FJHN, including family 1.
The disease complex medullary cystic disease/familial juvenile hyperuricemic nephropathy (MCKD/FJHN) is characterized by alteration of urinary concentrating ability, frequent hyperuricemia, tubulo-interstitial fibrosis, cysts at the cortico-medullary junction and renal failure.
Uromodulin-associated kidney disease (UAKD) is caused by mutations in the uromodulin (UMOD) gene that result in a misfolded form of UMOD protein, which is normally secreted by nephrons.
The clinical characteristics were similar to those of other patients suffering from uromodulin mutations and to those of patients suffering from medullary cystic kidney disease type 2 and familial juvenile hyperuricemic nephropathy.
Despite the unique location and recent association of THP gene mutations with hereditary uromodulin-associated kidney disease and THP single nucleotide polymorphisms with chronic kidney disease and hypertension, the physiological function(s) of THP and its pathological involvement remain incompletely understood.
FJHN is genetically heterogeneous and due to mutations of three genes: uromodulin (UMOD), renin (REN) and hepatocyte nuclear factor-1beta (HNF-1β) on chromosomes 16p12, 1q32.1, and 17q12, respectively.
The clinical characteristics were similar to those of other patients suffering from uromodulin mutations and to those of patients suffering from medullary cystic kidney disease type 2 and familial juvenile hyperuricemic nephropathy.
In a large Belgian family with FJHN, a tight linkage between the disorder and the marker D16S3060, located within the MCKD2 locus on chromosome 16p12 (maximal two-point logarithmic odds score of 3.74 at a recombination fraction of theta = 0), was observed in this study.
A mutation in the uromodulin gene (16p11-13) has recently been linked to medullary cystic kidney disease type 2 and familial juvenile hyperuricemic nephropathy.
Uromodulin (UMOD) mutations were described in patients with medullary cystic kidney disease (MCKD2), familial juvenile hyperuricemic nephropathy (FJHN), and glomerulocystic kidney disease (GCKD).
Furthermore, the genetic basis of familial juvenile hyperuricemic nephropathy (FJHN), glomerulocystic kidney disease (GCKD) and autosomal dominant medullary cystic kidney disease 2 (MCKD2) has been recently attributed to mutations within the THP gene.
UMOD mutations cause familial juvenile hyperuricemic nephropathy (FJHN) and medullary cystic kidney disease (MCKD), although these phenotypes are nonspecific.
Our results suggested that the novel uromodulin mutations found in the Chinese families lead to misfolded protein, which was retained in the endoplasmic reticulum, finally contributed to the phenotype of FJHN.