The CTLA-4 49 A/G polymorphism was detected by the PCR-restriction fragment-length polymorphism (RFLP) method in 97 type 1 diabetic subjects and 20 patients with Graves' disease, a cohort which included 4 patients who also had type 1 diabetes.
There was no evidence that the CTLA-4 exon 1 polymorphism (49 A/G) confers genetic susceptibility to type 1 diabetes mellitus in our case-control study in Japanese subjects.