4.465 ng/L; IQR 3.215, 7.332, p = 0.018), and soluble CD40 ligand and frequency of pain episodes (<3 episodes vs. ≥3 episodes in the past year: 0.398 ng/mL; IQR 0.308, 0.568 ng/mL vs. 0.543 ng/mL; IQR 0.434, 0.730 ng/mL, p = 0.039), but the previously observed association between MPTF procoagulant activity and acute chest syndrome was no longer significant (0.148 pg/mL; IQR 0.115, 0.274 pg/mL vs. 0.094 pg/mL; IQR 0.047, 0.155 pg/mL, p = 0.32). This evidence concerns the gene CD40LG and acute chest syndrome.