In 5 patients HCG was not administered and oocyte retrieval was cancelled; in 3 of these patients this was done to avoid severe ovarian hyperstimulation syndrome (OHSS); in 2 of these patients oocyte retrieval was cancelled; in 1 patient because of premature LH surge and in the other patient as a result of premature rise in progesterone (3.2 ng/ml) on planned day of HCG. The gene discussed is PLOD1; the disease is ovarian hyperstimulation syndrome.