There was a trend for different results among male and female patients regarding β-endorphin levels. Men with the minor allele TT tended to have higher β-endorphin levels (27.4 ± 3.40 fmol/L) than men with the major allele CC (25.8 ± 3.20 fmol/L). Similarly, women with the major allele CC tended to have higher β-endorphin levels (26.4 ± 3.30 fmol/L) than women with the minor TT allele (24.9 ± 3.66 fmol/L; Figure 2).
