ABSTRACT
A 24-year-old male visited our hospital because of pain in both flanks. His biochemistry profile showed an elevated serum creatinine level and low serum uric acid level. History taking revealed that he had undertaken exercise prior to the acute kidney injury (AKI) event, and he stated that family members had a history of urolithiasis. His renal profile improved after hydration and supportive care during hospitalization. Although the patient was subsequently admitted again due to AKI, his status recovered with similar treatment. Since the diagnosis of the patient was familial renal hypouricemia with exercise-induced AKI, we performed genotyping of SLC22A12, which encodes human urate transporter 1. The diagnosis was confirmed by the detection of a homozygous mutation of W258X. We herein, report a case of familial renal hypouricemia confirmed by genotyping of SLC22A12, and review the relevant literature.
Subject(s)
Humans , Male , Young Adult , Acute Kidney Injury , Biochemistry , Creatinine , Diagnosis , Hospitalization , Uric Acid , UrolithiasisABSTRACT
Objective To investigate a new single nucleotid polymorphism (SNP) intron5(+4668C/T) in SLC22A12 in primary gout patients and the association between clinical characteristics and genotypes. Methods One hundred and one primary gout patients and 186 healthy subjects were recruited into this study. Blood pressure, body mass index (BMI) was recorded. Serum uric acid, glucose, lipid and creatinine were detected. DNA was extracted from peripheral blood to amplify the fragment located in intron 5. The genotypes of SLC22A12 can be detected with high-resolution melting (HRM) assay, followed by sequencing analysis. Chi-square test was used for statistical analysis. Results ① A new SNP in intron 5 of SLC22A12 was identi-fied successfully by HRM, which was defined as intron 5 (+4668C/T). CC, CT and TT genotypes were unam-biguously distinguished with HRM technology, which was fully concordant with sequencing. ②The genotypes of CC, CT and TT in male and female groups were 28.1%, 33.7%, 38.2% and 20.0%, 47.1%, 32.9%, respectively.③ However, no significant differences of genotype distribution were found concerning BMI, blood pressure, creatinine, total cholesterol and triglyceride in both male group and female group. But the serum uric acid levels in the CC genotype were significantly higher than those with the CT+TT genotypes. ④ The genotype frequencies of CC and CT+TT in high uric acid group were remarkably different from those in low uric acid group (21.2%, 78.8%,; 35.0%, 65.0%; P<0.05). Conclusion A new SNP has been successfully discovered with HRM technology with simplicity, rapidity and accuracy. T allele of intron 5 (+4668C/T) may be a genetic protective factor for hyperuricemia among Chinese population.
ABSTRACT
Idiopathic renal hypouricemia is a disorder characterized by impaired urate handling in the renal tubules. This disease usually produces no symptoms, but hematuria, uric acid nephrolithiasis or acute renal failure may develop. A defect in the SLC22A12 gene, which encodes the human urate transporter, is the known major cause of this disorder. We describe a 10-month-old boy with idiopathic renal hypouricemia. He was diagnosed with transient pseudohypoaldosteronism at admission, but hypouricemia was accidentally found through follow-up study. By gene analysis, his diagnosis was confirmed to idiopathic renal hypouricemia. In addition, we report a mutation in the human urate transporter 1 (hURAT1) gene identified in his family.
Subject(s)
Humans , Infant , Male , Acute Kidney Injury , Diagnosis , Follow-Up Studies , Hematuria , Nephrolithiasis , Pseudohypoaldosteronism , Uric AcidABSTRACT
Idiopathic renal hypouricemia is a disorder characterized by impaired urate handling in the renal tubules. Most patients with hypouricemia are asymptomatic and are found incidentally, but the condition is known to be at high risk for exercise-induced acute renal failure or urolithiasis. URAT1 protein encoded by SLC22A12 gene has been identified recently as a urate/anion exchanger in the human kidney. Inactivation mutations in SLC22A12 gene have been shown to cause renal idiopathic hypouricemia. We experienced a 3-year-old boy who presented with persistent orange-colored urine since infancy. His urine contained many uric acid crystals, while the serum showed hypouricemia(0.7 mg/dL). The fractional excretion of uric acid was increased to 41.7%. SLC22a12 gene analysis revealed W258X homozygote alleles. Renal hypouricemia must be included in the differential diagnosis of red-urine and SLC22A12 gene analysis is recommended in idiopathic renal hypouricemia.