BACKGROUND
In this report, a Kazakh family with multigenerational clustering of diabetes mellitus was observed, strongly suggestive of a monogenic, heritable form such as maturity-onset diabetes of the young (MODY). Whole exome sequencing identified a heterozygous frameshift deletion in the hepatocyte nuclear factor 1 alpha (HNF1A) gene; benign or likely benign variants were detected in other MODY-associated genes. The HNF1A deletion was subsequently confirmed by Sanger sequencing. This finding provides a plausible molecular explanation for the familial diabetes phenotype and highlights the value of comprehensive genomic testing in clinically ambiguous cases.
CASE REPORT
A 6-year-old Kazakh girl was admitted after detection of persistent hyperglycemia during routine glucose testing. The patient had no history of diabetic ketoacidosis or classic symptoms of diabetes. Laboratory evaluation revealed elevated glycated hemoglobin and fasting plasma glucose levels, with preserved C-peptide secretion and negative autoimmune markers for type 1 diabetes mellitus. Due to the early onset of hyperglycemia and a multigenerational family history of diabetes, monogenic diabetes was suspected. The patient remained clinically stable; she was provided dietary recommendations and arranged for outpatient follow-up.
CONCLUSIONS
This report presents a rare case of MODY in a 6-year-old girl, highlighting the importance of considering monogenic diabetes in children with early-onset hyperglycemia, preserved β-cell function, and a positive family history. Early recognition and genetic testing are essential to establish an accurate diagnosis and guide appropriate management.

Keywords: Symptom Assessment; Diagnosis; Genetics, Medical; Diabetes Mellitus, Type 2; Rare Diseases; Gene Deletion; Endocrinology; Diabetes Mellitus, Type 2; Maturity-Onset Diabetes of the Young; Frameshift Mutation; Whole Exome Sequencing; HNF1A Protein, Human