Mutation analysis of SLC12A1 gene in nine Chinese patients with Bartter syndrome type Ⅰ / 中华肾脏病杂志

Objective To analyze the mutations of SLC12A1 gene in nine Chinese families with Bartter syndrome type I (BS1),and analyze the relationship between genotype and phenotype.Methods The next generation sequencing was used to detect mutations in nine BS1 patients including eight with antenatal BS (aBS) and one with classical BS (cBS).Clinical characteristics and biochemical findings at the first admission as well as follow-up were reviewed.Results 15 different mutations of SLC12A1 gene were identified,including 11 novel ones.Among nine probands,seven were compound heterozygotes,two were homozygotes.All patients presented with polydipsia and polyuria,and eight with growth retardation.All patients had lower than-normal serum chloride concentration,metabolic alkalosis,and elevated basal renin activity and aldosterone,and seven had hypokalemia.Through treatment of indomethacin and/or potassium chloride,biochemical indicators could roughly restored normal.Conclusion These findings will enrich the human gene mutation database (HGMD) and provide valuable references to the genetic counseling and diagnosis for Chinese population.

Gene analysis, treatment, and follow-up of sixteen Chinese patients with Bartter syndrome / 中华肾脏病杂志

Objective To analyze the mutations of causal genes in sixteen Chinese patients with suspicious Bartter syndrome,and follow up their treatment results.Methods Mutations were identified by the next generation sequencing and the multiplex ligation-dependent probe amplification (MLPA).Clinical and biochemical features at the first presentation as well as follow-up results were reviewed.Results 15 different CLCNKB gene mutations were identified in sixteen patients with BS,including 11 novel ones.A novel missense mutation and a novel small deletion were found from SLC12A1 gene.A novel gross deletion was found in CLCNKA gene.A recurrent missense mutation was identified from BSND gene.The whole gene deletion mutation of CLCNKB gene was the most frequent mutation (32％),and the rate of gross deletion was up to 50 percent in this group of Chinese patients.The most common clinical manifestations were development retardation (15/16),polydipsia and polyuria (15/16).All of the patients were detected with hypokalemia,hypochloremia and metabolic alkalosis.Indomethacin treatment had significant improvement to the stature and weight restoration.Conclusion The present study has found 19 mutations,including 14 novel ones,which enriches the human gene mutation database (HGMD) and provides valuable references to the genetic counseling and diagnosis of Chinese population.

A case of Bartter syndrome type I with atypical presentations / 소아과

Bartter syndrome (BS) is an autosomal recessively inherited rare renal tubular disorder characterized by hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism with normal to low blood pressure due to a renal loss of sodium. Genetically, BS is classified into 5 subtypes according to the underlying genetic defects, and BS is clinically categorized into antenatal BS and classical BS according to onset age. BS type I is caused by loss-of-function mutations in the SLC12A1 gene and usually manifests as antenatal BS. This report concerns a male patient with compound heterozygous missense mutations on SLC12A1 (p.C436Y and p.L560P) and atypical clinical and laboratory features. The patient had low urinary sodium and chloride levels without definite metabolic alkalosis until the age of 32 months, which led to confusion between BS and nephrogenic diabetes insipidus (NDI). In addition, the clinical onset of the patient was far beyond the neonatal period. Genetic study eventually led to the diagnosis of BS type I. The low urinary sodium and chloride concentrations may be caused by secondary NDI, and the later onset may suggest the existence of a genotype-phenotype correlation.