Basal FSH levels and ampoules of FSH used in COS for patients with variants of the FSH receptor. Basal FSH levels (left panel) and ampoules of FSH used in COS (right panel) for homozygote wild-type (Asn/Asn), heterozygote (Asn/Ser680) and homozygote (Ser680/Ser680) carriers of the Ser680 variant of the FSH receptor. ASN = asparagine; CPRs = clinical pregnancy rates; COS = controlled ovarian stimulation; FSH = follicle-stimulating hormone; r-FSH = recombinant follicle-stimulating hormone; Ser680 = Serine680. Adapted from Perez Mayorga et al. 2000 .