As a result, the effect of a recurrent short course of GnRH agonist therapy has been investigated [43]. Tahara et al. (2000) [43] investigated the decrease in endometriosis symptoms and differences in adverse effects in two groups of patients who were randomized to receive either full-dose nafarelin treatment (200 μg twice daily) for 24 weeks (n = 7) or full-dose nafarelin treatment for four weeks followed by half-dose nafarelin treatment (200 μg/day) for 20 weeks (n = 8). This evidence concerns the gene GNRH1 and endometriosis.