of Diabetes mellitus patients. To determine a MODY diagnosis, predict a probable clinical course and determine the family at risk, and identify a course of treatment, genetic analysis is needed.
Objectives: The Present study aims to detect mutation in exon 5 of hepatocyte nuclear factor -1- alpha (HNF1A) gene in suspected MODY3 cases.
Patients and methods: This case-control study, included 20 Egyptian diabetic patients and 10 healthy children as a control group. All cases were subject to full history taking, complete clinical examination and investigation as serum biomarkers for C-peptide assays, glycated hemoglobin (HbA1c), fasting and 2h post-prandial blood sugar levels, Anti-Gad and Anti-Islet antibodies and genetic analysis for HNF1A gene exon 5 revealed no abnormalities.
Results: The cases group included 9 males and 11 females, their mean age was 13.63±2.74 years, all cases (100%) had a positive family history of DM, and none had neonatal hypo or hyperglycemia and none had previous DKA. All cases were negative for Anti-Gad and Anti-Islet. The mean age on onset of DM was 11.08 ± 2.77 years, the mean duration of DM was 2.2 ± 0.16 years. 5% of cases were treated by oral hypoglycemic, 15 % were treated by insulin and oral hypoglycemic drugs, 15% were managed by healthy lifestyle and 65% of cases treated by insulin with a mean dose 0.34 ± 0.19. DNA sequencing of exon 5 reveals a normal exon with no variation detected.
 Conclusion: Due to phenotypic similarities, DNA sequencing for 10 Exons of HNF1A gene is advised if negative followed by Glucokinase (GCK), HNF1B, and HNF4A is strongly advised in cases where clinical suspicion of MODY exists.