Maturity-onset diabetes of the young





Introduction

Maturity-onset diabetes of the young (MODY) is characterised by the development of type 2 diabetes mellitus in patients < 25 years old. It is typically inherited as an autosomal dominant condition. Over six different genetic mutations have so far been identified as leading to MODY.

It is thought that around 1-2% of patients with diabetes mellitus have MODY, and around 90% are misclassified as having either type 1 or type 2 diabetes mellitus.

Classification

MODY 3
  • 60% of cases
  • due to a defect in the HNF-1 alpha gene
  • is associated with an increased risk of HCC

MODY 2
  • 20% of cases
  • due to a defect in the glucokinase gene

Clinical features

  • typically develops in patients < 25 years
  • a family history of early onset diabetes is often present
  • ketosis is not a feature at presentation
  • patients with the most common form are very sensitive to sulfonylureas, insulin is not usually necessary