A Novel UMOD Mutation (c.187T>C) in a Korean Family with Juvenile Hyperuricemic Nephropathy

Familial juvenile hyperuricemic nephropathy (FJHN; OMIM 162000) is an autosomal dominant disorder characterized by hyperuricemia and gouty arthritis due to reduced kidney excretion of uric acid and progressive renal failure. Gradual progressive interstitial renal disease, with basement membrane thickening and glomerulosclerosis resulting from fibrosis, starts in early life. In most cases of FJHN, uromodulin gene (UMOD) is responsible for the disease; however, there has been only one report of a genetically confirmed FJHN family in Korea. Here we report another Korean family with FJHN, in which three male members. a father and 2 sons.developed gout and progressive renal insufficiency. The clinical, laboratory, and radiological findings were consistent with FJHN, and renal biopsy showed chronic parenchymal damage, which can be found in FJHN but is not specific to this disease. In order to confirm the diagnosis, sequence analysis of the UMOD was performed, and a novel heterozygous missense variant (c.187T>C; p.Cys63Arg) in exon 3 was identified. We assume that this variant is likely to be the causative mutation in this family, as the variant segregated with the disease. In addition, approximately two-thirds of the known mutations lead to a cysteine amino acid change in uromodulin, and all such variants have been shown to cause UMOD-associated kidney disease. In summary, we report a Korean FJHN family with three affected members by genetic analysis of the UMOD, and provide the first report of a novel heterozygous missense mutation.