Familial renal glucosuria: a clinicogenetic study of 23 additional cases

Background Familial renal glucosuria (FRG) is an inherited renal tubular disorder characterized by persistent isolated glucosuria in the absence of hyperglycemia that is caused by mutations in the sodium-glucose cotransporter SGLT2 coding gene, SLC5A2 . Objective We conducted molecular and phenotype analyses of a cohort of 23 unrelated Korean children with FRG. Methods Mutational analysis of the SLC5A2 gene was conducted in this multicenter study organized by the Korean Society of Pediatric Nephrology. Results A total of 21 different SLC5A2 mutations were detected, including 19 novel mutations. All patients had at least one mutated allele; ten patients had homozygous or compound heterozygous mutations and 13 patients had a single heterozygous mutation. Most mutations were private. Patients with two mutations were diagnosed earlier with larger amounts of urinary glucose excretion than patients with single mutations. Pedigree analysis data were consistent with the inheritance of a codominant trait with incomplete penetrance. Conclusions These findings extend the allelic heterogeneity in FRG and confirm previous observations of inheritance and genotype–phenotype correlation in patients with this disease.