Evidence of IGF-IR involvement in TAO was observed by Weightman et al., Rotella et al., and Perros et al. who found that IgG collected from patients with GD (GD-IgG) could displace radiolabeled IGF-I from binding sites on the surfaces of orbital fibroblasts from extraocular muscles in both TAO and non-TAO patients [41–43]. This evidence concerns the gene IGF1 and thromboangiitis obliterans.