RESUMEN
OBJECTIVE: Leukaemia inhibitory factor (LIF) plays a central role in the control of implantation. We undertook this study to investigate the prevalence of LIF gene alterations in women with unexplained infertility and with recurrent failure of implantation after in vitro fertilisation (IVF) and embryo transfer. PATIENTS AND METHODS: Forty five women with recurrent failure of implantation after IVF (group A), 50 with unexplained infertility (group B) and 105 fertile women (controls) were screened for LIF gene mutations. Standard genomic DNA extraction, PCR amplification of the LIF gene and single-strand conformation polymorphism (SSCP) analysis were used to search for mutations which were subsequently confirmed by DNA sequencing. RESULTS: In group A, one woman was identified as having a neutral LIF gene polymorphism in exon 3 without affecting protein conformation. In group B, one woman with a heterozygous mutation and one with a neutral polymorphism were detected. In controls, only one woman with a neutral polymorphism in the intron between exons 2 and 3 was found. The woman with a potentially functional LIF gene mutation in group B achieved an ongoing clinical pregnancy after ovarian superovulation. DISCUSSION: Potentially functional mutations in the LIF gene do infrequently occur in women with unexplained infertility and may play a role in the etiology of infertility. However, routine screening for LIF mutations or polymorphisms in these women is not justified for the low prevalence of gene alterations.