Examples of genetic predisposition to SLE among different ethnicities influencing disease susceptibility and disease expression [26, 27] include the p53 gene in Koreans that was not replicable in a white population [28]; an association of the HSP70 gene in Africans and Spaniards that was not found among Mexicans; and the varying levels of significance of the protein receptor CTLA4 among Asians and whites [29]. The gene discussed is CTLA4; the disease is systemic lupus erythematosus.