In view of this potential mechanism to enhance HIF-1α levels and in view of the association of HIF-1α levels with breast cancer prognosis and resistance to treatment, we hypothesised that epigenetic silencing by promoter methylation for the SDH and FH genes may be a mechanism underlying upregulated HIF-1 in a proportion of breast carcinomas. The gene discussed is SDHB; the disease is breast carcinoma.