Mutations and polymorphisms in the gonadotrophin genes; clinical relevance

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.

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.

Clinical pharmacology of gonadotrophin preparations

The practice of ovulation induction and superovulation for IVF has progressed in many ways since the first reports of pregnancies after IVF over 25 years ago. The pharmacology of gonadotrophins has advanced alongside other developments, leading to safer, easier and more effective treatments for anovular infertility and IVF ovulation induction. This review uses current concepts of the basic physiology of gonadotrophin actions during the natural ovarian cycle as a starting point from which to assess their uses in anovulation and assisted reproduction. The relative merits of urinary and recombinant gonadotrophins are discussed, along with their uses in combination with gonadotrophin-releasing hormone agonists and antagonists.

The endocrine control of spermatogenesis

The hormonal regulation of spermatogenesis involves a complex interplay within the hypothalamo-pituitary-testicular axis, which commences before birth with male sexual development and continues through puberty and into adulthood. Hypothalamic gonadotrophin-releasing hormone drives these events by inducing pituitary gonadotrophin secretion, thereby stimulating testicular androgen secretion (providing virility) and spermatogenesis (providing fertility). Evidence from both animal models and man supports a need for both follicle-stimulating hormone and testosterone in achieving full spermatogenic potential, but a species difference in their relative roles exists. Clinical endocrine disorders can arise from a deficiency of hypothalamic gonadotrophin-releasing hormone and/or pituitary gonadotrophins, which results in hypogonadotrophic hypogonadism, featuring delayed/absent puberty and infertility. Physiologically-based and effective treatment with pulsatile gonadotrophin-releasing hormone or gonadotrophins can often restore fertility. Clinical conditions can also be caused by rare genetic disorders of the gonadotrophin molecules or the receptors for androgens and gonadotrophins, which result in a range of phenotypes (from male pseudohermaphroditism through to infertility); these disorders provide a unique insight into the physiology of sexual development and spermatogenesis.

Definition and measurement of follicle stimulating hormone

FSH has a key role in the development and function of the reproductive system and is widely used both diagnostically and therapeutically in developmental and reproductive medicine. The accurate measurement of FSH levels, in patients for diagnosis and monitoring and in therapeutic preparations for clinical use, is essential for safe and successful treatment. Historically, FSH was defined on the basis of classical in vivo endocrine activity, and early therapeutic preparations were calibrated using in vivo bioassays. There was early recognition that reference preparations were required for calibration if the results from different laboratories were to be comparable. In response to the perceived need, the World Health Organization established the first standard for such preparations in 1959. Subsequent developments in biotechnology have led to recognition that there is no single molecule that can be uniquely defined as FSH, and that FSH can induce a range of biological activities. Several highly purified standards for FSH are now available, but discontinuity and heterogeneity of estimates of FSH activity in terms of these standards made using in vitro assays and binding assays have been noted. It is thus essential that any measurement of FSH include specification both of the standard with which the measured FSH is compared and the assay method used for that comparison.