Molecular Diagnosis of Monogenic Diabetes and Clinical/Laboratory Features in Turkish Children

Objective: Monogenic diabetes is a heterogeneous disease that causes functional problems in pancreatic beta cells and hyperglycemia. The aim of this study was to determine the clinical and laboratory features, the admission characteristics and distribution of monogenic form of diabetes in childhood in Turkey. Methods: Patients aged 0-18 years, who were molecularly diagnosed with monogenic diabetes, and consented to participate, were included in the study. Results: Seventy-seven (45.6%) female and 92 male cases with a mean age of 8.18[+ or -]5.05 years at diagnosis were included. 52.7% of the cases were diagnosed with monogenic diabetes by random blood glucose measurement. The reason for genetic analysis in 95 (56.2%) of cases was having a family member diagnosed with diabetes under the age of 25. At the time of diagnosis, ketone was detected in urine in 16.6% of the cases. Mean hemoglobin A1c on admission, fasting blood glucose, fasting insulin, and c-peptide values were 7.3[+ or -]2.1%, 184.9[+ or -]128.9 mg/dL, 9.4[+ or -]22.9 IU/L, 1.36[+ or -]1.1 and ng/L respectively. GCK-MODY was found in 100 (59.2%), HNF1A-MODY in 31 (18.3%), and variants in ABCC8 in 6 (3.6%), KCNJ11 in 5 (3%), HNF4A in 2 (1.2%), and HNF1B in 2 (1.2%). Conclusion: Recent studies have indicated HNF1A-MODY is the most frequent of all the MODY-monogenic diabetes cases in the literature (50%), while GCK-MODY is the second most frequent (32%). In contrast to these reports, in our study, the most common form was GCK-MODY while less than 20% of cases were diagnosed with HNF1A-MODY. Keywords: Monogenic diabetes, early-onset diabetes, next-generation sequencing, GCK, HNF1A