With respect to the rs3087243 (+6230G>A) polymorphism of CTLA4, the first sister had type 1 diabetes and AITD and had the GG genotype, whereas the second and third sisters, who had type 1 diabetes without AITD, had the AG genotype.
Furthermore, a joint analysis, with the INS and CTLA4 SNPs, revealed that CTLA4 rs3087243, ERBB3 rs2292399, and CLEC16A rs2903692, but not INS rs689, were significant risk factors for the cooccurrence of AITD in Japanese T1D.