Also, HSV-1 infection is common in AD patients, and TLR9 recognizing CpG-sequences of viral DNA may activate MyD88 and TRIF-dependent pro-inflammatory signaling that further enhances skin inflammation in AD patients (David and Longson, 1985[34]; Wollenberg et al., 2003[220]). The gene discussed is TLR9; the disease is Alzheimer disease.