GENETICS OF NON-INSULIN-DEPENDENT DIABETE S-MELLITUS

Non insulin-dependent diabetes mellitus (NIDDM) is a genetic disorder with an epidemic development in the westernized civilisations. The kno wledge of genetic factors would help in screening those individuals su sceptible to develop diabetes, to prevent overfeeding, overweight and sedentarity ; these environmental factors can reveal or worsen diabete s. NIDDM is a clinically and genetically heterogeneous disorder, proba bly due to the alteration of several genes. The collection of numerous and large families with several diabetic subjects and the sorting in clinically homogeneous subgroups are necessary to identify the suscept ibility genes. It has been recently shown that glucokinase (enzyme tha t phosphorylates glucose in pancreatic beta-cell and liver) was the ca use of MODY (maturity onset diabetes of the young), a NIDDM subtype ch aracterized by an autosomic dominant mode of inheritance and an early age of onset. Glucokinase mutations are responsible for a mild hypergl ycemia with onset during childhood or during pregnancy; in addition, d iabetes can be due to mutations in mitochondrial DNA in families where the disease is maternally transmitted and often associated with heari ng loss. These two genetic defects can account for about 2 % to 5 % of NIDDM patients each. Screening for these mutations is feasible.