Familial Juvenile hyperuricemic nephropathy (FJHN, OMIM #162000) is a rare autosomal dominant disorder characterized by hyperuricemia with renal uric acid under-excretion, gout and chronic kidney disease. In most but not all families with FJHN, genetic studies have revealed mutations in the uromodulin (UMOD) gene located on chromosome 16p11-p13. We here described a novel heterozygous missense mutation (c.1382C>A causing p.Ala461Glu) in an affected 16-year-old male with hyperuricemia, gout and chronic kidney disease. His father was also affected and the UMOD mutation was found to segregate with the disease. There has been only one case report of Korean family with FJHN, which has not been diagnosed by genetic study. This is the first report of genetically diagnosed FJHN in Korea.
Adolescent ; Asian Continental Ancestry Group/*genetics ; Chromosomes, Human, Pair 16 ; Chronic Disease ; DNA Mutational Analysis ; Genes, Dominant ; Heterozygote ; Humans ; Hyperuricemia/*genetics ; Kidney Diseases/genetics ; Male ; *Mutation, Missense ; Pedigree ; Republic of Korea ; Uric Acid/blood ; Uromodulin/*genetics

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.
Adolescent ; Adult ; Base Sequence ; DNA Mutational Analysis ; Exons ; Gout/*genetics ; Heterozygote ; Humans ; Hyperuricemia/*genetics ; Kidney Diseases/*genetics ; Male ; *Mutation, Missense ; Pedigree ; Polymorphism, Single Nucleotide ; Republic of Korea ; Uromodulin/chemistry/*genetics

The effects of mangiferin on uric acid excretion, kidney function and related renal transporters were investigated in hyperuricemic mice induced by potassium oxonate. Mice were divided into normal control group, and 5 hyperuricemic groups with model control, 50, 100, and 200 mg x kg(-1) mangiferin, and 5 mg x kg(-1) allopurinol. Mice were administered by gavage once daily with 250 mg x kg(-1) potassium oxonate for seven consecutive days to create the model. And 3 doses of mangiferin were orally initiated on the day 1 h after potassium oxonate was given, separately. Serum uric acid, creatinine and urea nitrogon levels, as well as urinary uric acid creatinine levels were measured. Mouse uromodulin (mUMOD) levels in serum, urine and kidney were determined by ELISA method. The mRNA and protein levels of related renal transporters were assayed by RT-PCR and Western blotting methods, respectively. Compared to model group, mangiferin significantly reduced serum uric acid, creatinine and urea nitrogon levels, increased 24 h uric acid and creatinine excretion, and fractional excretion of uric acid in hyperuricemic mice, exhibiting uric acid excretion enhancement and kidney function improvement. Mangiferin was found to down-regulate mRNA and protein levels of urate transporter 1 (mURAT1) and glucose transporter 9 (mGLUT9), as well as up-regulate organic anion transporter 1 (mOAT1) in the kidney of hyperuricemic mice. These findings suggested that mangiferin might enhance uric acid excretion and in turn reduce serum uric acid level through the decrease of uric acid reabsorption and the increase of uric acid secretion in hyperuricemic mice. Moreover, mangiferin remarkably up-regulated expression levels of renal organic cation and carnitine transporters (mOCT1, mOCT2, mOCTN1 and mOCTN2), increased urine mUMOD levels, as well as decreased serum and kidney mUMOD levels in hyperuricemic mice, which might be involved in mangiferin-mediated renal protective action.
Animals ; Blood Urea Nitrogen ; Carrier Proteins ; genetics ; metabolism ; Creatinine ; blood ; Glucose Transport Proteins, Facilitative ; genetics ; metabolism ; Hyperuricemia ; blood ; chemically induced ; physiopathology ; urine ; Kidney ; metabolism ; physiopathology ; Male ; Membrane Proteins ; genetics ; metabolism ; Mice ; Octamer Transcription Factor-1 ; genetics ; metabolism ; Organic Anion Transport Protein 1 ; genetics ; metabolism ; Organic Anion Transporters ; genetics ; metabolism ; Organic Cation Transport Proteins ; genetics ; metabolism ; Organic Cation Transporter 2 ; Oxonic Acid ; Protective Agents ; pharmacology ; RNA, Messenger ; metabolism ; Random Allocation ; Solute Carrier Family 22 Member 5 ; Uric Acid ; blood ; urine ; Uromodulin ; blood ; urine ; Xanthones ; pharmacology