gene region on chromosome 2q33 has also been associated with T1D.
The locus that includes the CTLA-4 gene has been termed
IDDM12 (see slide summarizing genome screens).
CTLA-4 is a strong candidate gene for autoimmune diseases
because it encodes a T cell receptor that plays a role in controlling T
cell apoptosis (programmed cell death) and is a negative regulator of T
cell activation. Specifically, an
A49G polymorphism within the first exon of the CTLA-4 gene was
found to be associated with development T1D.
This polymorphism appears to increase T1D risk in multiple
populations, including the Italian, Spanish, French, Mexican-American,
and Korean populations.