Depression has been notably highlighted in this context, where baseline hypomethylation of two CpG sites within the serotonin receptor type 1A (HTR1A) and 1B (HTR1B) genes derived from whole blood was predictive of poor escitalopram response in a sample of Han Chinese patients with MDD after 8 weeks of treatment [174]. The gene discussed is HTR1B; the disease is major depressive disorder.