Final answer:
The majority of people with type 1 diabetes share alleles surrounding Major histocompatibility complex (MHC) genes, which are crucial for immune response and can predispose individuals to autoimmune diseases due to the presentation of autoantigens to T cells.
Step-by-step explanation:
The vast majority of people with type 1 diabetes share alleles surrounding the Major histocompatibility complex (MHC) genes. This is because type 1 diabetes is an autoimmune disorder where the immune system attacks the insulin-producing beta cells of the pancreas. Genetic susceptibility plays a significant role in the development of this autoimmune response, and certain alleles in the MHC region, particularly those involved in the immune system's ability to recognize self from non-self, are associated with an increased risk of developing type 1 diabetes.
MHC genes encode proteins essential for the immune system's ability to present antigens to T cells, which is crucial for the immune response. These genes are highly polymorphic, meaning that there are many different possible alleles that an individual can have, contributing to the diversity of immune responses among different individuals. However, certain MHC alleles can predispose individuals to autoimmune diseases like type 1 diabetes by presenting autoantigens to T cells, leading to an autoimmune attack on the body's own cells.