Phenotypic analysis of four peripheral blood mononuclear cell (PBMC) samples from four severe GO patients revealed the main subtype as CD4+ T cells (CD4/CD8 ratios 1.9-2.5), which was similar to the phenotypes of four control PBMC samples, whereas their corresponding orbital connective tissue-derived T cell lines had equal amounts of CD4+ and CD8+ T cells (CD4/CD8 ratios 0.9-1.2) (38). This evidence concerns the gene CD8A and geroderma osteodysplastica.