A common polymorphic allele of the human luteinizing hormone beta-subunit gene: additional mutations and differential function of the promoter sequence

Association of single-nucleotide polymorphisms in the ESR2 and FSHR genes with poor ovarian response in infertile Jordanian women

Objective

Poor ovarian response (POR) refers to a subnormal follicular response that leads to a decrease in the quality and quantity of the eggs retrieved after ovarian stimulation during assisted reproductive treatment (ART). The present study investigated the associations of multiple variants of the estrogen receptor 2 (ESR2) and follicle-stimulating hormone receptor (FSHR) genes with POR in infertile Jordanian women undergoing ART.

Methods

Four polymorphisms, namely ESR2 rs1256049, ESR2 rs4986938, FSHR rs6165, and FSHR rs6166, were investigated in 60 infertile Jordanian women undergoing ART (the case group) and 60 age-matched fertile women (the control group), with a mean age of 33.60±6.34 years. Single-nucleotide polymorphisms (SNPs) were detected by restriction fragment length polymorphism and then validated using Sanger sequencing.

Results

The p-value of the difference between the case and control groups regarding FSHR rs6166 was very close to 0.05 (p=0.054). However, no significant differences were observed between the two groups in terms of the other three SNPs, namely ESR2 rs1256049, ESR2 rs4986938, and FSHR rs6165 (p=0.561, p=0.433, and p=0.696, respectively).

Conclusion

The association between FSHR rs6166 and POR was not statistically meaningful in the present study, but the near-significant result of this experiment suggests that statistical significance might be found in a future study with a larger number of patients.

Role of gene polymorphisms related to progesterone elevation in women undergoing long GnRH agonist protocols

RESEARCH QUESTION

Can single-nucleotide polymorphisms (SNP) of genes related to progesterone synthesis predict the risk of premature serum progesterone elevation in women undergoing gonadotrophin-releasing hormone agonist protocols for ovarian stimulation?

DESIGN

A total of 765 women were divided into high progesterone and normal progesterone groups according to progesterone concentration on the day of human chorionic gonadotrophin (HCG) administration, with the 75th percentile as the threshold between the group. Associations were analysed of genetic information from whole exome sequencing and the clinical characteristics of the two groups to identify the relationship between SNP, haplotypes and serum progesterone elevation.

RESULTS

Among 40 common SNP of eight genes (FSHR, LHCGR, ESR1, ESR2, PGR, HSD3B1, CYP11A1 and CYP17A1), no statistical significance between the high and normal progesterone groups was identified in the distribution of genotypes and allele frequencies after multiple test correction to adjust the false discovery rate (P_FDR > 0.05). When compared with the most common haplotypes of each gene, haplotype GAAG in CYP17A1 was associated with a 1.44-fold increased risk of progesterone elevation (95% confidence interval [CI] 1.22-1.69, P_FDR < 0.001), while haplotypes of the following genes showed a decreased risk of progesterone elevation: haplotype CC in FSHR and LHCGR (0.66-fold, P_FDR = 0.020, and 0.64-fold, P_FDR < 0.001, respectively), CA in ESR1 (0.90-fold, P_FDR < 0.001), TCTGG in ESR2 (0.92-fold, P_FDR = 0.007) and GAACC in HSD3B1 (0.42-fold, P_FDR < 0.001).

CONCLUSIONS

Polymorphism in genes involved in enzymes or hormone receptors in the progesterone synthesis pathway may have a role in modifying risk of serum progesterone elevation.

Two Hormones for One Receptor: Evolution, Biochemistry, Actions, and Pathophysiology of LH and hCG

LH and chorionic gonadotropin (CG) are glycoproteins fundamental to sexual development and reproduction. Because they act on the same receptor (LHCGR), the general consensus has been that LH and human CG (hCG) are equivalent. However, separate evolution of LHβ and hCGβ subunits occurred in primates, resulting in two molecules sharing ~85% identity and regulating different physiological events. Pituitary, pulsatile LH production results in an ~90-minute half-life molecule targeting the gonads to regulate gametogenesis and androgen synthesis. Trophoblast hCG, the "pregnancy hormone," exists in several isoforms and glycosylation variants with long half-lives (hours) and angiogenic potential and acts on luteinized ovarian cells as progestational. The different molecular features of LH and hCG lead to hormone-specific LHCGR binding and intracellular signaling cascades. In ovarian cells, LH action is preferentially exerted through kinases, phosphorylated extracellular-regulated kinase 1/2 (pERK1/2) and phosphorylated AKT (also known as protein kinase B), resulting in irreplaceable proliferative/antiapoptotic signals and partial agonism on progesterone production in vitro. In contrast, hCG displays notable cAMP/protein kinase A (PKA)-mediated steroidogenic and proapoptotic potential, which is masked by estrogen action in vivo. In vitro data have been confirmed by a large data set from assisted reproduction, because the steroidogenic potential of hCG positively affects the number of retrieved oocytes, and LH affects the pregnancy rate (per oocyte number). Leydig cell in vitro exposure to hCG results in qualitatively similar cAMP/PKA and pERK1/2 activation compared with LH and testosterone. The supposed equivalence of LH and hCG has been disproved by such data, highlighting their sex-specific functions and thus deeming it an oversight caused by incomplete understanding of clinical data.

Profile of follitropin alpha/lutropin alpha combination for the stimulation of follicular development in women with severe luteinizing hormone and follicle-stimulating hormone deficiency

A severe gonadotropin deficiency together with chronic estradiol deficiency leading to amenorrhea characterizes patients suffering from hypogonadotropic hypogonadism. Administration of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) to these patients has been shown to be essential in achieving successful stimulation of follicular development, ovulation, and rescue of fertility. In recent years, the availability of both recombinant FSH (rFSH) and recombinant LH (rLH) has provided a new therapeutic option for the stimulation of follicular growth in hypopituitary–hypogonadotropic women (World Health Organization Group I). In this article, we review the data reported in the literature to highlight the role and the efficacy of using recombinant gonadotropins, rFSH and rLH, in the treatment of women with severe LH/FSH deficiency. Although the studies on this issue are limited and the experiences available in the literature are few due to the small number of such patients, it is clearly evident that the recombinant gonadotropins rFSH and rLH are efficient in treating patients affected by hypogonadotropic hypogonadism. The results observed in the studies reported in this review suggest that recombinant gonadotropins are able to induce proper follicular growth, oocyte maturation, and eventually pregnancy in this group of women. Moreover, the clinical use of recombinant gonadotropins in this type of patients has given more insight into some endocrinological aspects of ovarian function that have not yet been fully understood.

Impact of follicle-stimulating hormone receptor variants in female infertility

PURPOSE

Follicle-stimulating hormone (FSH) and its receptor play a major role in the development of follicles and regulation of steroidogenesis in the ovary and spermatogenesis in the testis. We aim to analyze the role of FSHR gene variants (single nucleotide polymorphisms (SNPs) in exon 10 (codon 307 and 680) and in the core promoter region (at position -29) and Ala189Val inactivating mutation) in Turkish infertile women. There were studies analyzing the effects of the SNPs in exon 10 (codon 307 and 680) and in the core promoter region (at position -29) of the FSHR gene on spermatogenesis, but to our knowledge, there were no studies analyzing the effects of these three SNP combinations on female fertility.

METHODS

In this study, the allelic, genotype, and haplotype frequency distributions of these three SNPs in the FSHR gene were analyzed in 102 infertile women and 99 unrelated healthy control individuals. The distribution of the polymorphisms was conformed by Hardy-Weinberg equilibrium test.

RESULTS

There were no statistical differences (P > 0.05) in the allele, genotype, and haplotype frequencies of the polymorphisms and FSH, luteinizing hormone (LH), estradiol (E2), and prolactin (PRL) levels between the infertile patients and the controls. However, a significant relation was found between 307 SNP GA genotype and FSH level ≥12. We did not find any homozygous or heterozygote mutations in infertile patients and healthy fertile controls.

CONCLUSION

The present study was the first study analyzing gma mutation and the polymorphism of the FSHR core promoter at position -29 alone and in combination with the two common SNPs in exon 10 in Turkish infertile women population. These findings indicate the significance of Ala307Thr GA genotype may be a predictive marker for poor ovarian reserve and infertility.

Impact of gene polymorphisms of gonadotropins and their receptors on human reproductive success

Gonadotropins and their receptors' genes carry several single-nucleotide polymorphisms resulting in endocrine genotypes modulating reproductive parameters, diseases, and lifespan leading to important implications for reproductive success and potential relevance during human evolution. Here we illustrate common genotypes of the gonadotropins and gonadotropin receptors' genes and their clinical implications in phenotypes relevant for reproduction such as ovarian cycle length, age of menopause, testosterone levels, polycystic ovary syndrome, and cancer. We then discuss their possible role in human reproduction and adaptation to the environment. Gonadotropins and their receptors' variants are differently distributed among human populations. Some hints suggest that they may be the result of natural selection that occurred in ancient times, increasing the individual chance of successful mating, pregnancy, and effective post-natal parental cares. The gender-related differences in the regulation of the reproductive endocrine systems imply that many of these genotypes may lead to sex-dependent effects, increasing the chance of mating and reproductive success in one sex at the expenses of the other sex. Also, we suggest that sexual conflicts within the FSH and LH-choriogonadotropin receptor genes contributed to maintain genotypes linked to subfertility among humans. Because the distribution of polymorphic markers results in a defined geographical pattern due to human migrations rather than natural selection, these polymorphisms may have had only a weak impact on reproductive success. On the contrary, such genotypes could acquire relevant consequences in the modern, developed societies in which parenthood attempts often occur at a later age, during a short, suboptimal reproductive window, making clinical fertility treatments necessary.

Identification of a novel ovine LH-beta promoter region, which dramatically enhances its promoter activity

The luteinizing hormone beta subunit (LH-beta) gene plays a critical role in reproduction. In order to characterize and analyze the promoter region of LH-beta in sheep, a genomic library was constructed in phage lambda gt 10 and screened. A novel region of 1,224 bp upstream from the targeted LH-beta gene was identified. Blasting this sequence showed a perfect homology for the first 721 bp sequence with an upstream ovine LH-beta sequence in the database. However, the remaining 5′-503 bp showed no sequence matching. DNA from Moroccan breeds was isolated and the whole region was amplified and confirmed by sequencing. To further confirm the promoter activity of this region, an in vitro analysis using a luciferase assay was carried out. An increase in the promoter activity of the whole region was demonstrated compared to the empty vector. More interestingly, the unpublished region significantly enhanced the promoter activity compared to the known region alone. To predict putative transcription factor binding-sites (TFBSs), an in silico analysis was performed using the TFSEARCH program. The region features many TFBSs and contains two palindrome sequences of 17- and 18-bp. Taken together, a novel region was identified and confirmed in sheep which contained a promoter activity rich with binding sites for a putative regulatory element as shown in silico.

'Carriers of variant luteinizing hormone (V-LH) among 1593 Baltic men have significantly higher serum LH'

Luteinizing hormone (LH) is a pituitary heterodimeric glycoprotein essential in male and female reproduction. Its functional polymorphic variant (V‐LH) is determined by two missense mutations (rs1800447, A/G, Trp8Arg; rs34349826, A/G, Ile15Thr) in the LH β‐subunit encoding gene (LHB; 19q13.3; 1111 bp; 3 exons). Among women, V‐LH has been associated with higher circulating LH and reduced fertility, but the knowledge of its effect on male reproductive parameters has been inconclusive. The objective of this study was to assess the effect of V‐LH on hormonal, seminal and testicular parameters in the Baltic young men cohort (n = 986; age: 20.1 ± 2.1 years) and Estonian idiopathic infertility patients (n = 607; 35.1 ± 5.9 years). V‐LH was detected by genotyping of the underlying DNA polymorphisms using PCR‐RFLP combined with resequencing of a random subset of subjects. Genetic associations were tested using linear regression under additive model and results were combined in meta‐analysis. No significant difference was detected between young men and infertility patients for the V‐LH allele frequency (11.0 vs. 9.3%, respectively). V‐LH was associated with higher serum LH in both, the young men cohort (p = 0.022, allelic effect = 0.26 IU/L) and the idiopathic infertility group (p = 0.008, effect = 0.59 IU/L). In meta‐analysis, the statistical significance was enhanced (p = 0.0007, resistant to Bonferroni correction for multiple testing; effect = 0.33 IU/L). The detected significant association of V‐LH with increased serum LH remained unchanged after additional adjustment for the SNPs previously demonstrated to affect LH levels (FSHB ‐211G/T, FSHR Asn680Ser, FSHR ‐29A/G). Additionally, a suggestive trend for association with reduced testicular volume was observed among young men, and with lower serum FSH among infertility patients. The V‐LH carrier status did not affect sperm parameters and other circulating reproductive hormones. For the first time, we show a conclusive contribution of V‐LH to the natural variance in male serum LH levels. Its downstream clinical consequences are still to be learned.

Gene polymorphisms in female reproduction

This chapter presents an overview of the gene polymorphisms underlying the functions of ovarian receptors and their clinical implications in the female fecundity. A selection of genetic studies revealing significant associations between receptor polymorphisms, gene mutations, and some pathological conditions (i.e., female infertility, premature ovarian failure, polycystic ovary syndrome, endometriosis) are reviewed.

Hormonal, functional and genetic biomarkers in controlled ovarian stimulation: tools for matching patients and protocols

Variability in the subfertile patient population excludes the possibility of a single approach to controlled ovarian stimulation (COS) covering all the requirements of a patient. Modern technology has led to the development of new drugs, treatment options and quantitative methods that can identify single patient characteristics. These could potentially be used to match patients with the right treatment options to optimise efficacy, safety and tolerability during COS. Currently, age and follicle-stimulating hormone (FSH) level remain the most commonly used single patient characteristics in clinical practice. These variables only provide a basic prognosis for success and indications for standard COS treatment based on gross patient categorisation. In contrast, the anti-Müllerian hormone level appears to be an accurate predictor of ovarian reserve and response to COS, and could be used successfully to guide COS. The antral follicle count is a functional biomarker that could be useful in determining the dose of FSH necessary during stimulation and the success of treatment. Finally, in the future, genetic screening may allow an individual patient's response to stimulation during COS to be predicted based on genotype. Unfortunately, despite the predictive power of these measures, no single biomarker can stand alone as a guide to determine the best treatment option. In the future, hormonal, functional and genetic biomarkers will be used together to personalise COS.

Effects of polymorphisms in gonadotropin and gonadotropin receptor genes on reproductive function

Gonadotropins, the action of which is mediated at the level of their gonadal receptors, play a key role in sexual development, reproductive functions and in metabolism. The involvement of the gonadotropins and their receptor genotypes on reproductive function are widely studied. A large number of gonadotropins and their receptors gene polymorphisms are known, but the only one considerable as a clear, absolute genetic marker of reproductive features or disfunctions is the FSHR Asn680Ser polymorphism, since it modulates ovarian response to FSH. The aim of these studies would to be the prediction of the genetic causes of sex-related diseases to enable a customized clinical setting based on individual response of patients undergoing gonadotropin stimulation. In this review we discuss the latest information about the effects of polymorphisms of the gonadotropins and their receptor genes on reproductive functions of both male and female, and discuss their patho-physiological implications.

Who needs LH in ovarian stimulation?

LH plays a key role in the intermediate-late phases of folliculogenesis. Although ovarian stimulation is efficiently achieved in most cases by the administration of exogenous FSH alone, specific subgroups of women may benefit from LH activity supplementation during ovarian stimulation. Some authors have found improved outcome with LH activity supplementation in advanced reproductive age women. Experience suggests that in about 10-12% of young normogonadotrophic patients treated with a gonadotrophin-releasing hormone agonist (GnRH-a) long protocol plus recombinant FSH human (r-hFSH), a 'steady response' is observed. In this subgroup of women, a higher number of oocytes is retrieved when daily LH activity supplementation is given from stimulation day 8, if compared with the standard FSH dose increase. Another subgroup of patients who may benefit from LH activity supplementation are those at risk for poor ovarian response treated with GnRH antagonist. Recent data demonstrate that in these women, when GnRH is administered in a flexible protocol, the concomitant addition of recombinant human LH improves the number of mature oocytes retrieved, when compared with the standard GnRH-a flare-up protocol. Thus, well calibrated LH administration improves the ovarian outcome in patients >35 years, in those showing an initial abnormal ovarian response to r-hFSH monotherapy, and in 'low prognosis' women treated with GnRH antagonists.

Individualised controlled ovarian stimulation (iCOS): maximising success rates for assisted reproductive technology patients

BACKGROUND

In the last two decades, pregnancy rates for patients undergoing in-vitro fertilisation (IVF) have significantly increased. Some of the major advances responsible for this improvement were the introduction of controlled ovarian stimulation (COS) for the induction of multiple follicle development, and the utilisation of mid-luteal gonadotropin-releasing hormone agonists to achieve pituitary down-regulation and full control of the cycle. As a result, a combination of a gonadotropin-releasing hormone agonist with high doses (150-450 IU/day) of recombinant follicle-stimulating hormone has become the current standard approach for ovarian stimulation. However, given the heterogeneity of patients embarking on IVF, and the fact that many different drugs can be used alone or in different combinations (generating multiple potential protocols of controlled ovarian stimulation), we consider the need to identify special populations of patients and adapt treatment protocols accordingly, and to implement a more individualised approach to COS.

DISCUSSION

Studies on mild, minimal and natural IVF cycles have yielded promising results, but have focused on fresh embryo transfers and included relatively young patient populations who generally have the potential for more favourable outcomes. The efficacy of these protocols in patients with a poorer prognosis remains to be tested. When comparing protocols for COS, it is important to think beyond current primary endpoints, and to consider the ideal quality and quantity of oocytes and embryos being produced per stimulated patient, in order to achieve a pregnancy. We should also focus on the cumulative pregnancy rate, which is based on outcomes from fresh and frozen embryos from the same cycle of stimulation. Individualised COS (iCOS) determined by the use of biomarkers to test ovarian reserve has the potential to optimise outcomes and reduce safety issues by adapting treatment protocols according to each patient's specific characteristics. As new objective endocrine, paracrine, functional and/or genetic biomarkers of response are developed, iCOS can be refined further still, and this will be a significant step towards a personalised approach for IVF.

CONCLUSIONS

A variety of COS protocols have been adopted, with mixed success, but no single approach is appropriate for all patients within a given population. We suggest that treatment protocols should be adapted for individual patients through iCOS; this approach promises to be one of the first steps towards implementing personalised medicine in reproductive science.

Genomics and genetics of gonadotropin beta-subunit genes: Unique FSHB and duplicated LHB/CGB loci

The follicle stimulating hormone (FSH), luteinizing hormone (LH) and chorionic gonadotropin (HCG) play a critical role in human reproduction. Despite the common evolutionary ancestry and functional relatedness of the gonadotropin hormone beta (GtHB) genes, the single-copy FSHB (at 11p13) and the multi-copy LHB/CGB genes (at 19q13.32) exhibit locus-specific differences regarding their genomic context, evolution, genetic variation and expressional profile. FSHB represents a conservative vertebrate gene with a unique function and it is located in a structurally stable gene-poor region. In contrast, the primate-specific LHB/CGB gene cluster is located in a gene-rich genomic context and demonstrates an example of evolutionary young and unstable genomic region. The gene cluster is shaped by a constant balance between selection that acts on specific functions of the loci and frequent gene conversion events among duplicons. As the transcription of the GtHB genes is rate-limiting in the assembly of respective hormones, the genomic and genetic context of the FSHB and the LHB/CGB genes largely affects the profile of the hormone production.

An association study between the genetic polymorphisms within GnRHI, LHβ and FSHβ genes and central precocious puberty in Chinese girls

OBJECTIVES

Gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are three hypothalamic-pituitary-gonadal axis expressing hormones. They play critical roles in the onset of puberty. Here we report the relationship between the three hormones and Central Precocious Puberty (CPP) in Chinese Han girls.

METHODS

We analyzed the single nucleotide polymorphisms (SNPs) of 5'-flanking regions of these genes by DNA sequencing in 27 CPP samples. Then the SNPs sites were genotyped by ligase detection reaction in a total of 283 Chinese Han CPP cases and 284 matched controls. Distributions of the polymorphisms and haplotypes were calculated for statistical evaluation.

RESULTS

Nine SNPs (One in GnRHI gene: -2003 C/T; Five in LHβ gene: -1456 C/G, -1424 C/G, -238 G/A, -164 G/A and -34 T/A; Three in FSHβ gene: -1825 T/C, -261 G/T and -132 T/A.) were found. A quantitative genetic association study was made. -1825 T/C in FSHβ gene was related with CPP with a weak effect (P=0.025). A haplotype in the 5'-flanking region of LHβ gene was significantly associated with CPP in Chinese Han girls (P=8.25×10(-09)). However, analysis software showed that none of SNP was found in the regulating control element of these genes.

CONCLUSIONS

Our finding implies that the polymorphisms in the 5'-flanking regions of FSHβ gene and LHβ gene probably were related to the puberty onset time of these girls. Further studies on the polymorphisms are needed for the exact mechanism.

Outcomes after early or midfollicular phase LH supplementation in previous inadequate responders

Second cycle outcomes of 75 patients who had previous inadequate ovarian response with recombinant FSH (rFSH)-only ovarian stimulation during gonadotrophin-releasing hormone analogue (GnRHa) down-regulated cycles were evaluated retrospectively. In these second cycles, both rFSH and human menopausal gonadotrophin (HMG) in GnRHa long down-regulation were given to all patients, HMG initiated either on day 1 (group A, n=37) or day 5-6 of the ovarian stimulation (group B, n=38). Total HMG dose was higher (1198+/-514 IU versus 726+/-469 IU; P<0.001), cumulative rFSH consumption was lower (1823+/-804 IU versus 2863+/-1393 IU; P=0.001) and duration of stimulation was shorter (8.94+/-1.15 days versus 10.37+/-1.80 days; P<0.001) in group A than in group B. No significant differences were found regarding fertilization, implantation or pregnancy rates and embryo quality between the groups. Further analysis by supplementary HMG dose (75 IU versus 150 IU) revealed that total gonadotrophin and HMG consumption was lower in 75 IU-supplemented subgroups. Notably, pregnancy rate was higher in patients where 75 IU HMG was supplemented on day 5-6 of ovarian stimulation, which deserves further evaluation.

New insights into the evolution of chorionic gonadotrophin

The glycoprotein hormones luteinizing hormone (LH) and chorionic gonadotrophin (CG) are crucial for reproduction, as LH induces sex hormone production and ovulation, and CG is essential for the establishment of pregnancy and fetal male sexual differentiation. Both consist of two heterodimeric peptides of which the alpha-subunit is common to both hormones whereas the beta-subunit is hormone-specific. The CGB gene was derived from LHB by gene duplication and frame shift mutation that led to a read-through into the formerly 3'-untranslated region, giving rise to the carboxyl-terminal peptide. Owing to nucleotide changes within the 5'-region of CGB, a new transcriptional start site and regulatory region was gained. These changes led to the specific expression of CGB in the placenta and its decrease in the pituitary. Recent findings on gonadotrophins led to an extended model for the sequence of events in the evolution of the CGB gene in primates and its tissue-specific expression.

Understanding the role of LH: myths and facts

This review summarizes a series of lectures given at a recent Continuing Medical Education meeting in Hamburg, Germany (May 2007), aiming to understand the role of luteinizing hormone (LH) in follicular development during the natural menstrual cycle and controlled ovarian stimulation. Clinical situations and target groups of patients who might benefit from LH supplementation during their ovarian stimulation were discussed and defined. The lectures updated knowledge on the physiology of LH during the normal menstrual cycle and the role of LH in ovarian stimulation. The concept of the 'LH window' was presented, and the use of LH supplementation in different groups of patients undergoing controlled ovarian stimulation was discussed, including those with advanced age, hypogonadotrophic hypogonadism, pituitary down-regulation and poor response. In addition, the different ways of using LH or human chorionic gonadotrophin supplementation in ovulation induction protocols were described.

Is there a need for recombinant human luteinizing hormone (lutropin alfa) supplementation in ovarian stimulation for assisted reproduction?

Luteinizing hormone is now available as the recombinant product, lutropin alfa for the treatment of female infertility. It is necessary in the natural process of follicular growth and maturation. It is not yet clear which patients really benefit from the addition of this medication to conventional gonadotropin stimulation procedures in infertility treatment. Certainly, it has a proven benefit in patients suffering from hypogonadotropic hypogonadism (WHO I). Others may be older patients, patients with a profound gonadotropin suppression stimulated in long gonadotropin-releasing hormone agonist protocols, or patients with poor ovarian response to conventional stimulation strategies. The available data are reviewed herein.

Exploiting LH in ovarian stimulation

During intermediate-late phases of human folliculogenesis, LH plays a key role in promoting steroidogenesis and growth of the leading follicle. Ovarian stimulation for assisted reproduction techniques usually consists of administering exogenous FSH in a low LH environment. Although an impairment in LH-dependent paracrine activities would be expected, multiple follicular growth is efficiently achieved in almost all patients. Thus, there appears to be a discrepancy between classical folliculogenesis models and data from IVF. This study examines the 'interface' between basic endocrinological and clinical evidence, in an attempt to answer two questions: is there an LH therapeutic window, and if there is, how can this be exploited in the practice of assisted reproduction? It also reviews the evidence that specific subgroups of women may benefit from LH supplementation during ovarian stimulation.

Who needs LH in ovarian stimulation?

LH plays a key role in the intermediate-late phases of folliculogenesis. Although ovarian stimulation is efficiently achieved in most cases by the administration of exogenous FSH alone, specific subgroups of women may benefit from LH activity supplementation during ovarian stimulation. Some authors have found improved outcome with LH activity supplementation in advanced reproductive age women. Experience suggests that in about 10-12% of young normogonadotrophic patients treated with a gonadotrophin-releasing hormone agonist (GnRH-a) long protocol plus recombinant FSH human (r-hFSH), a 'steady response' is observed. In this subgroup of women, a higher number of oocytes is retrieved when daily LH activity supplementation is given from stimulation day 8, if compared with the standard FSH dose increase. Another subgroup of patients who may benefit from LH activity supplementation are those at risk for poor ovarian response treated with GnRH antagonist. Recent data demonstrate that in these women, when GnRH is administered in a flexible protocol, the concomitant addition of recombinant human LH improves the number of mature oocytes retrieved, when compared with the standard GnRH-a flare-up protocol. Thus, well calibrated LH administration improves the ovarian outcome in patients >35 years, in those showing an initial abnormal ovarian response to r-hFSH monotherapy, and in 'low prognosis' women treated with GnRH antagonists.

To add or not to add LH: comments on a recent commentary

From a period of time when LH activity supplementation in stimulation protocols for assisted reproductive technology was questioned, recent scientific evidence seems to prove a role of LH activity in optimizing the clinical results of certain subgroups. Until now, apart from the hypogonadotrophic hypogonadal patient, two subgroups of patients have attracted attention: patients over 35 years of age, and normogonadotrophic patients with an initial low response to recombinant FSH (rFSH). However, in a recent paper, another subgroup of patients has been identified: normogonadotrophic patients with high endogenous LH levels (>1.99 IU/l) on day 8 of stimulation after a long GnRH agonist down-regulation. By adding recombinant LH (rLH) from day 8 to the stimulation protocol, this subgroup of patients achieved good implantation rates, similar to those of patients with lower LH levels. Interestingly, the dynamics of the endogenous LH levels during down-regulation in this group of patients differed from those of patients with lower LH levels. The immunoreactivity of the LH molecule does not necessarily reflect the bioactivity, which might explain the beneficial effect of LH activity supplementation in patients with high endogenous LH levels after down-regulation. Future studies should be focused on subgroups to further explore the effect of LH activity supplementation in assisted reproduction techniques.

Association of common LH variant with hyperfunctional promoter in a Japanese infertile woman

A common LH variant (V-LH) with Trp8Arg and Ile15Thr is often associated with ovarian dysfunction primarily in the Japanese population, and the LHB gene encoding V-LH is linked with a hyperfunctional promoter that could partly compensate for the somewhat weak biological effect of the V-LH in the Finnish and other several populations. We analyzed the promoter region in a Japanese infertile woman homozygous for the V-LH, to examine whether the hyperfunctional promoter is present or absent in the Japanese V-LH carriers with ovarian dysfunction. Direct sequencing was performed for a 661 bp promoter region from -8 to -668 bp of LHB, revealing homozygosity for eight nucleotide substitutions (-238A>G, -276G>A, -489C>A, -490T>A, -504T>A, -506T>C, -525T>G, and -552C>T) that are identical to those found in the hyperfunctional promoter. The results suggest that ovarian dysfunction frequently observed in the Japanese V-LH carriers would be due to some population-specific genetic and/or environmental factor(s) rather than to the lack of the hyperfunctional promoter and the resultant low biological effect of the V-LH. In addition, the tight linkage between the two missense substitutions in the coding region and the eight nucleotide substitutions in the promoter region of LHB appears to be common to various ethnic groups.

Does variant luteinizing hormone (V-LH) predispose to improper testicular position in late pregnancy?

Undescended testes are a common urogenital malformation affecting 2-9% of newborn boys. The etiology of cryptorchidism is probably heterogeneous, but insufficient androgen effect has been recognized as one cause of the condition. A common genetic variant (V) form of LH occurs in apparently healthy individuals universally. Compared with wild-type (WT) LH, the V-LH molecule has increased bioactivity in vitro but shorter half-life in vivo. In the present study, we screened 93 cryptorchid (59 uni- and 34 bilateral) and 211 healthy boys for the occurrence of V-LH to evaluate whether it is related to testicular descent. Two immunofluorometric assays with different combinations of MAb, one detecting WT-LH, the other detecting both WT- and V-LH, were used to measure LH concentrations. The ratio of two LH measurements was used to assess the V-LH status. The prevalence of V-LH was similar in the control and cryptorchid groups, and the total prevalence of V-LH corresponded well to the prevalence of V-LH in general Finnish population. Among cryptorchid boys, the prevalence of V-LH was dependent on gestational age: 6.7% at GA <37, 20.9% at GA 37-39, and 42.9% at GA of 40-42 wk. In contrast, the percentage of V-LH status was similar at different gestational ages in all control groups. We conclude that V-LH is not critical for normal testicular descent but the increased prevalence of V-LH among cryptorchid boys with GA >40, suggests that the lower hormonal efficacy of V-LH predisposes for improper testicular descent in late pregnancy.

Recombinant human LH supplementation versus recombinant human FSH (rFSH) step-up protocol during controlled ovarian stimulation in normogonadotrophic women with initial inadequate ovarian response to rFSH. A multicentre, prospective, randomized controlled trial

BACKGROUND

In approximately 12-14% of young normogonadotrophic women treated with a depot GnRH agonist long protocol, the initial ovarian response to recombinant human FSH (rFSH) can be suboptimal. We have tested the hypothesis that these women may benefit from recombinant human LH (rLH) supplementation in a multicentre, prospective, randomized trial compared with patients treated with an rFSH step-up protocol.

METHODS

A total of 260 young normogonadotrophic women undergoing controlled ovarian stimulation with a GnRH agonist long protocol for IVF/ICSI were enrolled. The starting dose of rFSH was 225 IU. One hundred and thirty patients with serum estradiol levels <180 pg/ml and with at least six follicles with a mean diameter >5 mm but none >10 mm on both day 5 and day 8 of stimulation were randomly allocated to two groups. From the eighth day of stimulation, women in group A (n=65) received 150 IU of rLH in addition to rFSH, while those in group B (n=65) had an increase of 150 IU in the daily dose of rFSH (step-up protocol). One hundred and thirty normally responding women continued monotherapy with rFSH and served as a further control population (group C).

RESULTS

The mean number of cumulus-oocyte complexes retrieved in group A (9.0+/-4.3) was significantly higher (P<0.01) compared with group B (rFSH 6.1+/-2.6) but significantly lower compared with group C (10.49+/-3.7, P<0.05). Implantation and pregnancy rates were significantly lower (P<0.05) in the rFSH step-up group (10.5 and 29.3% respectively) when compared with normal responders (18.1 and 47.3% respectively).

CONCLUSIONS

rLH supplementation is more effective than increasing the dose of rFSH in terms of ovarian outcome in patients with an initial inadequate ovarian response to rFSH alone.

Absence of the genetic variant Val79Met in human chorionic gonadotropin-beta gene 5 in five European populations

Chorionic gonadotropin (CG) is an essential signal in establishment and maintenance of pregnancy in humans and higher primates. A G-to-A transition in exon 3 of human CGbeta gene 5, changing the naturally occurring valine residue to methionine in codon 79 (Val(79)Met) has been reported at carrier frequency 4.2% in a random population from the Midwest of the United States. The biological activity of the variant hCG was similar to that of wild-type (WT) hCG. However, the Val(79)Met beta-subunit displayed impaired ability to assemble with alpha-subunit, and the amount of hCG alpha/beta heterodimers formed and secreted by transfected cells was seriously impaired in the previous study. Because of these functional implications we found it important to study the occurrence of the Val(79)Met hCGbeta variant in other populations. By using a PCR-RFLP method, a search for the Val(79)Met hCGbeta variant was carried out on a total of 580 DNA samples from five European populations (Finland, Denmark, Greece, Germany and the UK). The results demonstrated an absence of the polymorphism in these populations. Hence, the naturally occurring variant (Val(79)Met) of the hCGbeta gene 5, found previously at high frequency in the US, is clearly less common, or absent, in the European populations studied.

Effects of recombinant LH (rLH) supplementation during controlled ovarian hyperstimulation (COH) in normogonadotrophic women with an initial inadequate response to recombinant FSH (rFSH) after pituitary downregulation

BACKGROUND

This study was aimed to evaluate the effect of different recombinant LH (rLH) doses on the ovarian outcome of normogonadotrophic women with an initial inadequate response to recombinant FSH (rFSH) after pituitary downregulation.

METHODS

Only women undergoing a 'long protocol' with a GnRH-agonist followed by rFSH administration were enrolled. On the eighth day of stimulation, 46 patients with serum E2 levels < 180 pg/ml and with no follicle > 10 mm were randomized in two groups to receive a supplementation with a daily rLH dose of 75 (group A) or 150 IU (group B), respectively. Forty-six normal responders continuing their monotherapy with rFSH formed the control group (C).

RESULTS

The mean number of oocytes retrieved and the percentage of mature oocytes in the group B (9.65 +/- 2.16, 79.0%) were comparable with those observed in the group C (10.65 +/- 2.8, 82.5%) and significantly higher when compared with the group A (6.39 +/- 1.53, 65.7%). The mean number of ampoules of rLH was significantly higher in the group B (14.4 +/- 2.0 vs. 9.65 +/- 1.1), whereas these patients received a significantly lower mean number of rFSH ampoules (44.6 +/- 7.4 vs. 36.1 +/- 3.8). Seven (30.4%), 9 (39.1%) and 22 (47.8%) pregnancies were achieved in the groups A, B and C, respectively.

CONCLUSIONS

These results suggest that patients with initial inadequate responses to rFSH after pituitary downregulation benefit from the addition of a daily dose of 150 IU of rLH, starting from the eighth day of stimulation.

Luteinizing hormone beta polymorphism and risk of familial and sporadic prostate cancer

BACKGROUND

Circulating testosterone plays an important role in maintenance and growth of prostate cells. Luteinizing hormone (LH), secreted from the anterior pituitary, signals testicular Leydig cells to secrete testosterone. A genetic variant of the LH-beta protein, LH-betaV, exists in up to 40% of Caucasians and is more bioactive than the wild-type protein. We hypothesized that genetically determined variation in LH function might affect susceptibility to prostate cancer via altered testosterone secretion.

METHODS

We determined the frequency of the LH-betaV polymorphism (two linked polymorphisms: Trp(8) --> Arg and Ile(15) --> Thr) in familial prostate cancer patients (n = 446), in sporadic prostate cancer patients (n = 388), and in population-based controls without prostate cancer (n = 510) to assess the role of this polymorphism in susceptibility to prostate cancer.

RESULTS

A higher frequency of this variant genotype (LH-betaV: Arg(8)/Thr(15)) was observed in familial prostate cancer patients (18.6%) than in controls (13.7%), and after taking into account the correlation of the familial cases and adjusting for age and body mass index (BMI), there was a weak positive association between the variant LH-beta genotype, and risk of familial prostate cancer (OR = 1.29; 95% CI 0.96-1.75). The sporadic case group was also slightly more likely to have a variant genotype (15.2%) compared to the controls (13.7%), and after adjustment for age and BMI, a similar association with this variant was found (OR = 1.33; 95% CI 0.86-02.07). Surgical cases showed a slightly stronger association for the variant LH-beta genotype compared to non-surgical cases, but among the surgical cases there was little variability in risk across nodal status, stage, and tumor grade.

CONCLUSIONS

These data are consistent with the hypothesis that the LH-beta variant is a weak risk factor for prostate cancer.

Influence of missense mutation and silent mutation of LHbeta-subunit gene in Japanese patients with ovulatory disorders

The frequency of variant LHbeta containing two point mutations (T(986)-C and T(1008)-C) and its relationship to reproductive disorders differ widely between ethnic groups. In a Japanese population, variant luteinizing hormone (LH) correlates with ovulatory disorders. Here we examined the relationship between two missense mutations and five silent mutations (C(894)-T, G(1018)-C, C(1036)-A, C(1098)-T and C(1423)-T) in the LHbeta gene, and ovulatory disorders. We studied 43 patients with ovulatory disorders, 79 patients with normal ovulatory cycles, and 23 healthy men who agreed to join our DNA analysis. PCR-amplified LHbeta-subunit gene sequences were compared with a base sequence of wild-type LH reported after direct sequencing. The highest frequency (0.945) of novel allele was observed at the position of the C(1036)-A transition. No homozygotes for wild-type LHbeta (C(1036)) were identified. The frequency of novel allele in patients with polycystic ovary syndrome, endometriosis, premature ovarian failure and luteal insufficiency was significantly different from that of healthy women. The frequencies of novel alleles (C(894)-T, C(1098)-T and C(1423)-T) in patients with ovulatory disorders were significantly higher than those with normal ovulatory cycles. The mean incidence of point mutation in patients with ovulatory disorders was higher than in those with normal ovulatory cycles. Among patients with variant LH, five silent mutations were identified in 87.5% of patients with ovulatory disorders, whereas only a few silent mutations were identified in patients with normal ovulatory cycles. In a Japanese population, five silent mutations of variant LH could have influenced two missense mutations and/or other unknown missense mutations, causing ovulatory disorders.

Different signaling pathways control acute induction versus long-term repression of LHbeta transcription by GnRH

GnRH regulates pituitary gonadotropin gene expression through GnRH receptor activation of the protein kinase C (PKC) and calcium signaling cascades. The pulsatile pattern of GnRH release is crucial for induction of LHbeta-subunit (LHbeta) gene expression; however, continuous prolonged GnRH exposure leads to repression of LHbeta gene transcription. Although in part, long-term repression may be due to receptor down-regulation, the molecular mechanisms of this differential regulation of LHbeta transcription are unknown. Using transfection into the LH-secreting immortalized mouse gonadotrope cell line (LbetaT4), we have demonstrated that LHbeta gene transcription is increased by acute activation (6 h) of GnRH receptor or PKC but not calcium influx; in contrast long-term activation (24 h) of GnRH receptor, PKC, or calcium influx each repress LHbeta transcription. Whereas blockade of PKC prevented the acute action of GnRH and unmasked an acute repression of LHbeta transcription by calcium, it did not prevent long-term repression by GnRH or calcium. Removal of calcium resulted in potentiation of acute GnRH and PKC induction of LHbeta gene expression but prevented long-term repression by GnRH and reduced long-term repression by either calcium or 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We conclude that GnRH uses PKC for acute induction, and calcium signaling is responsible for long-term repression of LHbeta gene expression by GnRH. Furthermore, analysis of the responsiveness of truncated and mutated LHbeta promoter regions demonstrated that not only do acute induction and long-term repression use different signaling systems, but they also use different target sequences for regulating the LHbeta gene.

Lack of association of the common immunologically anomalous LH with endometriosis

BACKGROUND

Subfertile women with endometriosis have been reported to demonstrate impaired follicular growth, ovulatory dysfunction and disturbed LH patterns. In addition, abnormal LH and/or LH receptors have been linked with endometriosis-associated infertility. Carriers of a variant of the beta-subunit of luteinizing hormone (V-LH) are largely healthy; however, differences in their gonadal function such as alterations in gonadal steroidogenesis, ovarian reserve, pubertal development and predisposition to diseases such as infertility and polycystic ovarian disease have been found.

METHODS AND RESULTS

To explore the possible relationship between endometriosis and V-LH, we examined its frequency in 230 women undergoing laparoscopic surgery for the investigation of infertility. For the entire study population, 185 (80.4%) were wild type; 42 (18.3%) were heterozygous; and three (1.3%) were homozygous for V-LH. No difference was found between women with (n = 85) and without (n = 145) endometriosis concerning the frequency of the type of LH.

CONCLUSION

Our results do not support the hypothesis that the variant form of LH is associated with an altered risk of endometriosis in the population tested.

Rescue of IVF cycles by HMG in pituitary down-regulated normogonadotrophic young women characterized by a poor initial response to recombinant FSH

BACKGROUND

The aim of this study was to investigate the effects of adding human menopausal gonadotrophin (HMG) during controlled ovarian stimulation in normoovulatory normogonadotrophic patients showing an initial suboptimal response to a standardized long protocol therapy with recombinant FSH (rFSH) (300 IU/day).

METHODS

A total of 43 such patients were randomized in two groups. In Group A, 150 IU rFSH was substituted by 150 IU HMG after day 8 of stimulation. The stimulation protocol of Group B involved a simple increase of the daily rFSH dose to 375 IU after day 8. A total of 40 BMI and age matched patients with an optimal ovarian response formed the control group (Group C).

RESULTS

The mean Group A serum concentration of oestradiol on the day of HCG administration and average number of oocytes retrieved were significantly higher than Group B (P < 0.001) and equivalent to Group C. A total of 10 pregnancies (50%) in Group A, 8 (34.8%) in Group B and 19 (47.5%) in the control group were achieved.

CONCLUSIONS

The data suggest that LH supplementation improves the ovarian outcome in patients characterized by an inadequate initial response to rFSH therapy in a long protocol.

A common genetic variant of luteinizing hormone; relation to normal and aberrant pituitary-gonadal function

Mutations of the luteinizing hormone (LH) subunit genes are extremely rare. Only one polymorphic LHbeta gene variant makes an exception. In 1992, an immunologically anomalous form of LH was found in a healthy woman, and it was subsequently found to be caused by two point mutations leading to two amino acid substitutions in the LHbeta subunit. Of the two point mutations, Trp(8)Arg and Ile(15)Thr, the first one is mainly responsible for the altered immunoreactivity and the latter one introduces an extra glycosylation site into Asn(13) of the mutated LHbeta peptide. The frequency of this variant LHbeta allele differs widely between ethnic groups, being most common in aboriginal Australians (carrier frequency >50%; allelic frequency 28.3%) and totally lacking from Kotas of Southern India. Functional differences have been detected when wild-type LH and variant LH have been compared. Variant LH possesses increased in vitro bioactivity, whereas its half-life in circulation is shorter in comparison to wild-type LH. Also the regulation of the variant LHbeta gene differs due to additional changes in its promoter sequence. Correlations of occurrence of variant LH with various clinical conditions involving LH function suggest that it represents a biologically less active form of LH and may be related to borderline suppression of gonadal function, including subfertility. In this article, we will review the current information about the differences observed in structure and functions between the wild-type and variant LH, as well as their possible pathophysiological correlations.

Mutations of gonadotropins and gonadotropin receptors: elucidating the physiology and pathophysiology of pituitary-gonadal function

The recent unraveling of structures of genes for the gonadotropin subunits and gonadotropin receptors has provided reproductive endocrinologists with new tools to study normal and pathological functions of the hypothalamic-pituitary-gonadal axis. Rare inactivating mutations that produce distinctive phenotypes of isolated LH or FSH deficiency have been discovered in gonadotropin subunit genes. In addition, there is a common polymorphism in the LHbeta subunit gene with possible clinical significance as a contributing factor to pathologies of LH-dependent gonadal functions. Both activating and inactivating mutations have been detected in the gonadotropin receptor genes, a larger number in the LH receptor gene, but so far only a few in the gene for the FSH receptor. These mutations corroborate and extend our knowledge of clinical consequences of gonadotropin resistance and inappropriate gonadotropin action. The information obtained from human mutations has been complemented by animal models with disrupted or inappropriately activated gonadotropin ligand or receptor genes. These clinical and experimental genetic disease models form a powerful tool for exploring the physiology and pathophysiology of gonadotropin function and provide an excellent example of the power of molecular biological approaches in the study of pathogenesis of diseases.