IFNG and systemic lupus erythematosus: Among the different single nucleotide polymorphisms (SNP) related to IFN-γ, IFN-γ +874 T/A (rs2430561) is related to not only systemic lupus erythematosus [19,20], Grave’s disease [21,22] and thyroiditis of Hashimoto [22], but it has also been proven to be associated with the A allele, producing lower levels of IFN-γ at a protein level compared with those that have the T allele.