HTR2A and myalgic encephalomeyelitis/chronic fatigue syndrome: Among the CNS-related genes, the highest measures of genetic effects on CFS prediction were provided by SNPs in HSD11B1 (rs846906), HTR2A (rs1923884), MAOB (rs1799836), CRHR1 (rs1396862), SLC18A2 (rs363236), NOS3 (rs891512), and DRD2 (rs1124492).