The major histocompatibility complex class I polypeptide-related sequence B (MICB) rs1051788 polymorphism demonstrates pleiotropic effects, with allele A correlated with an elevated likelihood of schizophrenia and allele G in relation to elevated antibody titres for HSV-1 in healthy subjects (p = 0.006, OR = 2.7). The gene discussed is MICB; the disease is schizophrenia.