Prevalence and phenotypic features of diabetes due to recessive, non-syndromic WFS1 mutations

OBJECTIVE: Recessive WFS1 mutations are known to cause Wolfram syndrome, a very rare systemic disorder. However, they were also found in non-syndromic diabetes in Han Chinese misdiagnosed with type 1 diabetes (T1D), a molecular cause that appears to be considerably more common than the fully expressed syndrome. We aimed to better define the incidence and clinical features of non-syndromic diabetes due to recessive WFS1 mutation. DESIGN: We analyzed the genotype and phenotype of 320 consecutive incident Chinese pediatric diabetic patients diagnosed from 2016 to 2019 to search for non-syndromic diabetic cases due to recessive WFS1 mutation. METHODS: A cohort of 105 pancreatic autoantibody-negative patients were recruited for exome sequencing. All patients tested positive for pathogenic diallelic WFS1 mutations were examined for phenotypic features (fundoscopy, audiogram, and urine density). RESULTS: We found three cases of non-syndromic diabetes due to recessive WFS1 mutations (incidence = 0.94% (95% CI: 0.25-2.7%)). All three cases only had mild diabetes when diagnosed. All patients had well-conserved fasting C-peptide when diagnosed but one of them progressed to T1D-like insulin deficiency. In addition, we found a fourth case with previously undetected features of Wolfram syndrome. CONCLUSIONS: Non-syndromic diabetes due to WFS1 mutation may be common among Chinese pediatric patients with diabetes. It is important to differentiate it from other maturity-onset diabetes in the young subtypes with similar phenotype by molecular diagnosis because of different prognosis and, potentially, therapy.