Objective: To explore the genetic basis for an infant with permanent neonatal diabetes mellitus (PNDM).
Methods: Clinical data of the child was collected. Targeted capture-next generation sequencing was carried out to identify the potential variants. Candidate variant was verified by Sanger sequencing of her family members.
Results: The child was a 4-month-and-26-day female featuring onset of ketoacidosis accompanied with fasting blood glucose of 24.4 mmol/L, positive urine glucose, decreased serum C-peptide, HbA1c of 9.58%, and negative diabetes autoantibody. Genetic testing revealed that she has carried a heterozygous c.314T>G (p.L105R) variant of the INS gene. Sanger sequencing verified that neither of her parents has carried the same variant, which was also unreported in the literature. The variant was classified as likely pathogenic based on the ACMG guidelines.
Conclusion: The c.314T>G (P.L105R) variant of the INS gene probably underlay the genetic etiology in this child. Genetic testing should be conducted for children with suspected PNDM for early diagnosis and appropriate treatment.