Type 1 Diabetes Mellitus (T1D)

Type 1 (insulin-dependent) Diabetes Mellitus (T1D) is a complex, multifactorial disorder where many genetic and environmental factors are involved.

Type 1 Diabetes Mellitus is the most common form of diabetes among children and young adults among Caucasians, where the prevalence is approximately 0.4%. This incidence varies geographically and by age: prevalence in China and Venezuela is 0.1/100,000 cases while it reaches 36/100.000 in Sardinia and Finland. The disease is characterized by subtotal (> 80%) or total destruction of the ß-cells of the pancreas Langherans islets caused by a lymphocytic insulitis (autoantibodies).

Genetics of Type 1 Diabetes Mellitus

The genetic predisposition has a very important role in the aetiology of Type 1 Diabetes Mellitus and, even if more than 40 gene loci have been associated to the disease, the HLA region, due to the extreme polymorphism of its genes, contributes from 30 up to 50% to the genetic susceptibility to this disease.

The role of Class II HLA

The highest probability to develop Type 1 Diabetes Mellitus is associated to the presence of the DRB1*04-DQA1*03-DQB1*03:02 and DRB1*03-DQA1*05-DQB1*02 haplotypes in heterozygosis (serologically known as DR4-DQ8 and DR3-DQ2), followed by the DR4-DQ8 homozygote and finally by the DR3-DQ2 homozygote.