Although use of GnRH antagonists in some controlled clinical trials showed that the frequency of the severe form of OHSS is lower than in case when agonists are used, one cannot exclude a probability that such results are a consequence of possibility that agonists are often used instead of hCG in protocols with antagonists as ovulation triggers, which may itself reduce incidence of OHSS.21 However, patient’s predisposition for developing OHSS is still considered as the most probable factor which is also in line with our results. The gene discussed is GNRH1; the disease is ovarian hyperstimulation syndrome.