A single study awaiting replication reported the association between tics and a single nucleotide polymorphism (SNP) of the TNF gene (−308 A/G) coding for the pro-inflammatory cytokine tumor necrosis factor (TNF-α), which controls its transcription and has been linked to atopic dermatitis, asthma, and Graves' disease (25). The gene discussed is TNF; the disease is atopic eczema.