Table 3.

DNA methylation alterations in autoimmune disease.

Autoimmune disease	DNA methylation/alteration	VOCs linked with DNA methylation/alteration	Consequences	Examples of affected genes
Lupus	Hypomethylation	Acetonitrile, toluene, hexane, 2-methylpentane, methyl cyclopentane and 3-methylpentanetoluene, benzene, xylene, mercury, vinyl chloride, perchloroethylene, trichloroethylene, and crystalline silica	Gene activation	CD70, CD154, IL-4, IL-6, CD9, and MMP9 (cytokines and signaling molecules)
Lupus	Hypermethylation	Cadmium, vinyl chloride, perchloroethylene, trichloroethylene, smoking, silica dust, pesticides, and exposure to livestock	Gene silencing	RUNX3 (folate biosynthesis genes), IL-2, and foxp3 (Treg generation)
Rheumatoid arthritis	Hypomethylation	Crystalline silica, vinyl chloride, perchloroethylene, trichloroethylene, and smoking	Gene activation	CD40L, IL-6, and IL-1 (cytokines and signaling molecules)
Type 1 diabetes	Hypermethylation	Toluene, benzene, xylene, petroleum hydrocarbon products, fuel vapor, and gasoline	Gene silencing	Insulin and foxp3 (Treg generation, insulin production in pancreatic cells)
Vitiligo	Hypermethylation	Monobenzyl ether of hydroquinone or monobenzone	Gene activation	NLRP1 and PTPN22 (regulate inflammatory response and signal transduction)
Pernicious anemia (PA)	Hypermethylation	Petroleum hydrocarbon products, fuel vapor, and gasoline	Gene activation	Many genes are affected depending on the type of PA such as FCGR2A, PTPN22, SERPINA1, IL12B, P4HA2 PRTN3, etc.
Vasculitis	Hypermethylation	New building scent and nitric acid	Gene activation	HLA-DP and HLA-DQ variants, SERPINA1, PRTN3, and PTPN22
Alopecia areata	Hypermethylation	Cooling and heating systems and household goods	Gene activation	PRDX5 and STX17 (hair follicle-specific genes)