Introduction: Maturity-onset diabetes of the young (MODY) is a form of monogenic diabetes typically affecting young adults. There are 14 different genes that lead to pancreatic cell dysfunction causing MODY. Occurrence of MODY12 by ATP binding cassette subfamily C member 8 (ABCC8) gene is rare, comprising 1% of all the MODY subtypes. Case: A 13-year-old male was incidentally found to be hyperglycemic during medical examination. He denied any hyperosmolar symptoms, polyphagia, nocturia and recurrent skin infection. He did not have any history of neonatal diabetes mellitus. His father had been diagnosed with type 1 diabetes mellitus at the age of 22 years old. On examination, he is thinly built with no goiter or acanthosis nigricans. HbA1c was 8.8%. His insulin antibodies were negative. Whole exome sequencing revealed a heterozygous missense mutation in ABCC8 gene (c.2209G>A; p.Val737Ile), where there was a single nucleotide mutation of Valine to Isoleucine at the position 737 of the ABCC8 gene. This variant was reported in the ClinVar database as having uncertain significance. Considering the patient’s clinical features, this mutation is responsible for the disease. He was initially treated with sulfonylurea, namely glibenclamide; however, his continuous glucose monitoring was not optimized and required change to insulin therapy. Conclusion This case explores the phenotypic spectrum of ABCC8- related MODY, showing that this mutation can present without neonatal diabetes and emphasizing the requirement of insulin as part of treatment. Genetic testing should be conducted in patients presenting with atypical clinical features of diabetes mellitus to initiate personalized treatment strategies.
Mason-Type Diabetes