Objective  To analyze the clinical manifestations and molecular basis of a patient with primary renal glucosuria (PRG).

  Methods  Clinical features, laboratory data, and imaging results were collected. Genomic DNA was extracted from leukocytes of peripheral blood of the patient. Fourteen exons of the PRG gene and their boundaries with introns were amplified by polymerase chain reaction (PCR). The mutations of the SLC5A2 gene were identified by direct sequencing.

  Results  PRG was diagnosed on the basis of comprehensive consideration of clinical presentations, laboratory test results, and imaging findings. Gene mutation test revealed a nucleotide substitution of guanine for adenine at the position 877 of cDNA sequence of SLC5A2 gene (c.877 A>G), which caused a missense mutation of serine to cysteine at codon 293 (p.Ser293Cys). It occurred at the 7th exon of SLC5A2. Loci conservation analysis and functional prediction of missense mutation of SLC5A2 protein revealed that p.Ser293Cys was a pathogenic mutation.

  Conclusions  SLC5A2 gene mutation analysis confirms the diagnosis of PRG in this patient from the aspect of molecular genetics.It is important to suspect PRG in patients with renal glucosuria and normal blood glucose in the absence of other manifestations ofproximal renal tubular dysfunction.Genetic analysis of SLC5A2 may be helpful to confirm the diagnosis.