Subsequently, we evaluated the expression patterns of BDNF and TrKB at different stages of endometriosis and examined whether there are correlations between BDNF or TrKB and endometriosis severity or dysmenorrhoea, with the goal of providing a theoretical basis for the aetiological mechanism of endometriosis and the treatment of endometriosis-related pain. The gene discussed is BDNF; the disease is endometriosis.