A) Bisulfite sequencing of the BCL-2 P1 promoter region. B). Bisulfite sequencing was performed across 38 CpG sites from genomic DNA isolated from LCLs of discordant MZ twins. Autistic co-twins are designated by A_ preceding the blood identifier number (e.g., A_809); undiagnosed co-twins are designated by M_ preceding the blood number (e.g., M_810). Control (C) individuals include unaffected siblings (e.g., C_813), one normal monozygotic twin pair (C_2744 and C_2745). A pair of siblings, one autistic (A_2020) and one unaffected (C_2019), was also included in this analysis. Inset: average percentage methylation with sd across all 38 CpG sites for each group of samples.