Ovarian resistance to luteinizing hormone: a novel cause of amenorrhea and infertility

Genetic variants of G-protein coupled receptors associated with pubertal disorders

Background

The human hypothalamic-pituitary-gonadal (HPG) axis is the regulatory center for pubertal development. This axis involves six G-protein coupled receptors (GPCRs) encoded by KISS1R, TACR3, PROKR2, GNRHR, LHCGR, and FSHR.

Methods

Previous studies have identified several rare variants of the six GPCR genes in patients with pubertal disorders. In vitro assays and animal studies have provided information on the function of wild-type and variant GPCRs.

Main Findings

Of the six GPCRs, those encoded by KISS1R and TACR3 are likely to reside at the top of the HPG axis. Several loss-of-function variants in the six genes were shown to cause late/absent puberty. In particular, variants in KISS1R, TACR3, PROKR2, and GNRHR lead to hypogonadotropic hypogonadism in autosomal dominant, recessive, and oligogenic manners. Furthermore, a few gain-of-function variants of KISS1R, PROKR2, and LHCGR have been implicated in precocious puberty. The human HPG axis may contain additional GPCRs.

Conclusion

The six GPCRs in the HPG axis govern pubertal development through fine-tuning of hormone secretion. Rare sequence variants in these genes jointly account for a certain percentage of genetic causes of pubertal disorders. Still, much remains to be clarified about the molecular network involving the six GPCRs.

Ovarian macrocysts and gonadotrope-ovarian axis disruption in premenopausal women receiving mitotane for adrenocortical carcinoma or Cushing's disease

CONTEXT

Mitotane is an adrenolytic and anticortisolic drug used in adrenocortical carcinoma (ACC), Cushing's disease (CD), and ectopic ACTH syndrome. Its effects on the ovaries are unknown.

OBJECTIVE

To evaluate the ovarian and gonadotrope effects of mitotane therapy in premenopausal women.

PATIENTS

We studied 21 premenopausal women (ACC: n=13; CD: n=8; median age 33 years, range 18-45 years) receiving mitotane at a median initial dose of 3 g/day (range 1.5-6 g/day).

METHODS

Gynecological history was collected and ovarian ultrasound was performed. Four women also underwent ovarian CT or magnetic resonance imaging. Serum gonadotropin, estradiol (E2), androgens, sex hormone-binding globulin (SHBG), and circulating mitotane levels were determined at diagnosis and during mitotane therapy.

RESULTS

In the women included, ovarian macrocysts (bilateral in 51%) were detected after a median 11 months (range: 3-36) of mitotane exposure. The median number of macrocysts per woman was two (range: 1-4) and the median diameter of the largest cysts was 50 mm (range: 26-90). Menstrual irregularities and/or pelvic pain were present in 15 out of 21 women at macrocyst diagnosis. In two women, the macrocysts were revealed by complications (ovarian torsion and hemorrhagic macrocyst rupture) that required surgery. Mitotane therapy was associated with a significant decrease in androstenedione and testosterone levels and a significant increase in LH levels. Serum FSH and E2 levels were also increased, and SHBG levels rose markedly.

CONCLUSIONS

Mitotane therapy causes significant morphological and ovarian/gonadotrope hormonal abnormalities in premenopausal women. Follicular thecal steroid synthesis appears to be specifically altered and the subsequent increase in gonadotropins might explain the development of macrocysts. The mechanisms underlying these adverse effects, whose exact prevalence in this population still needs to be determined, are discussed.

Effect of luteinizing hormone/choriogonadotropin receptor (LHCGR) gene on chicken reproductive traits

Luteinizing hormone/choriogonadotropin receptor (LHCGR) gene, potentially related to reproductive traits in chickens, was genotyped by using the Pooled DNA Sequencing, PCR-SSCP and Directing Sequencing techniques. 306 Erlang Mountain chickens form one line (SD03, a line that has been selected for egg quality from a local chicken breed in Sichuan province, China) were genotyped in this study. The associations between LHCGR polymorphisms and six reproductive traits [body weight at first egg (BWAFE), weight of first egg, age at first egg (AFE), number of eggs at 300 days of age (EN), body weight at 300 days of age and egg weight at 300 days of age (EWTA)] were estimated using the one-way analysis of variance method. Results showed that SNP +G4058A and SNP +T4099G of the LHCGR gene were significantly associated with BWFE and AFE. Birds with the AG genotype for the +G4058A SNP exhibited shorter AFE (P < 0.05) and greater EN than those of the GG and AA genotypes, suggesting a balancing selection (overdominance); the effect of allele C in SNP +C3021T and allele C in SNP +T4490C on EN and AFE is additive and may reflect the influence of positive selection. These alleles have promise as genetic markers for future marker-assisted selection.

Chromosomal abnormalities in women with premature ovarian failure

Premature ovarian failure is a complex disorder that results in the early loss of ovarian function; however this disease must be separated from early menopause because these patients can sporadically ovulate and in literature are described pregnancies. The aetiology and the patho-physiology of premature ovarian failure are still matter of debate, but is commonly accepted that genetic factors play an important role. This review is aimed to present an overview of known inherited factor implied in the pathogenesis of this disorder to help physician in the counselling of affected pregnant women.

46,XY DSD due to impaired androgen production

Disorders of androgen production can occur in all steps of testosterone biosynthesis and secretion carried out by the foetal Leydig cells as well as in the conversion of testosterone into dihydrotestosterone (DHT). The differentiation of Leydig cells from mesenchymal cells is the first walk for testosterone production. In 46,XY disorders of sex development (DSDs) due to Leydig cell hypoplasia, there is a failure in intrauterine and postnatal virilisation due to the paucity of interstitial Leydig cells to secrete testosterone. Enzymatic defects which impair the normal synthesis of testosterone from cholesterol and the conversion of testosterone to its active metabolite DHT are other causes of DSD due to impaired androgen production. Mutations in the genes that codify the enzymes acting in the steps from cholesterol to DHT have been identified in affected patients. Patients with 46,XY DSD secondary to defects in androgen production show a variable phenotype, strongly depending of the specific mutated gene. Often, these conditions are detected at birth due to the ambiguity of external genitalia but, in several patients, the extremely undervirilised genitalia postpone the diagnosis until late childhood or even adulthood. These patients should receive long-term care provided by multidisciplinary teams with experience in this clinical management.

Disorders of sexual differentiation in the adolescent

Disorders of sexual differentiation (DSDs) presenting during adolescence are discussed, and molecular explanations are given for some. DSD conditions are often discovered during early adolescence, an age well known to predispose to high risk for adjustment problems. Presentation may be with lack of or minimal pubertal development, lack of menarche, vaginal, uterine, or breast agenesis and inappropriate sexual development such as virilization in females or feminization (gynecomastia) in males. Most such disorders require life-long therapy, with many of the medical, surgical and psychological aspects of management being accentuated during adolescence. Regardless of the age at presentation, all require skillful management to promote normal health and well-being. This care ideally involves specialists in endocrinology and medical therapy, psychology and, if required, surgery. A brief discussion of the needs of the adolescent with DSDs is presented.

Premature ovarian failure associated with autoimmune polyglandular syndrome: pathophysiological mechanisms and future fertility

BACKGROUND

Autoimmune polyglandular syndromes (APS) are a series of disorders characterized by autoimmunity against two or more endocrine organs. Premature ovarian failure (POF) may also have an autoimmune origin and, when accompanied by other autoimmune endocrinopathies, may be part of the APSs. Onset of autoimmune ovarian failure usually occurs in childhood, adolescence, or adulthood, and as a result, fertility may be severely compromised.

CASE REPORT

A 26-year-old women with secondary amenorrhea, Addison's disease, and autoimmune hypothyroidism requested infertility evaluation. Examination, transvaginal ultrasonography, endocrine evaluation, and ovarian biopsy were performed. 21-Hydroxylase and antithyroid antibodies were demonstrated, but ovarian steroid cell antibodies (StCA) were absent at the time of her infertility evaluation. Transvaginal sonography demonstrated only a few ovarian follicles. An ovarian biopsy revealed lymphocytic infiltration of the ovary. This presentation is consistent with APS type II accompanied by autoimmune POF.

DISCUSSION

Unlike APS types I and III, autoimmune POF is more commonly encountered with APS types I and III than with APS type II. An autoimmune response to steroidogenic enzymes and ovarian steroid cells appears to mediate destruction of ovarian function. Although immunotherapy with corticosteroids (with or without in vitro fertilization [IVF]) may be successful in limited cases where several follicles are present, oocyte donation with IVF may be the best option for the patient seeking fertility, particularly in the absence of ovarian follicles.

CONCLUSIONS

Advances in molecular genetics may be valuable in predicting and counseling women at risk for APS and POF, and cryopreservation of ovarian tissue may offer hope to affected unmarried young women. It is reasonable to suggest that children and reproductive aged women with one autoimmune disorder should be periodically screened for other autoimmune disorders.

Premature ovarian failure is not premature menopause

Normal menopause occurs at an average age of 50 and results from ovarian follicle depletion. Normal menopause is an irreversible condition, whereas premature ovarian failure is characterized by intermittent ovarian function in half of these young women. These young women produce estrogen intermittently and sometimes even ovulate despite the presence of high gonadotropin levels. Indeed, pregnancy has occurred after a diagnosis of premature ovarian failure. On pelvic ultrasound examination, follicles were equally likely to be detected in patients more than 6 years after a diagnosis of premature ovarian failure as in patients less than 6 years after the diagnosis. Thus, the probability of detecting a follicle appears to remain stable during the normal reproductive lifespan of these young women. Indeed, pregnancy was reported in a 44-year-old woman 16 years after a diagnosis of premature ovarian failure. No treatment to restore fertility in patients with premature ovarian failure has proved to be safe and effective in prospective controlled studies. Theoretically, these unproved therapies might even prevent one of these spontaneous pregnancies from occurring.

Molecular defects causing ovarian dysfunction

The functions of the hypothalamic-pituitary-ovarian and -adrenal axes are intertwined, and molecular defects in either axis may cause ovarian dysfunction. Advances in molecular genetics have allowed new insights into the pathophysiology of ovarian disorders. Specific gene mutations causing delayed puberty and/or ovarian failure, and heterosexual or isosexual precocious puberty have recently been described. The molecular insights gained into ovarian dysfunction have already led to rational therapies for some of these conditions.

Clinical features of women with resistance to luteinizing hormone

OBJECTIVE

To review clinical and hormonal characteristics of new and published females with LH resistance.

PATIENTS

Seven sisters of patients with male pseudohermaphroditism due to LH resistance.

MEASUREMENTS

Clinical characteristics, hormonal levels, pelvic ultrasound and molecular studies.

RESULTS

Patients had: (1) normal female external genitalia; (2) spontaneous breast and pubic hair development at ages 9-13 years; (3) menarche at 12-20 years, followed by irregular menstrual cycles (3 weeks to 15 months); (4) infertility; (5) withdrawal bleeding after progesterone administration; (6) elevated serum LH levels (10-38 IU/l, normal 0. 9-8.4) and elevated LH/FSH ratio with normal androgen levels; (7) low or normal oestradiol levels for the follicular phase; and (8) normal or small uterus and normal or increased ovary size with one or more cysts at ultrasound examination. Ovarian biopsy showed antral follicles and confirmed lack of ovulation. One homozygous mutation in exon 11 of the LH receptor gene was found in each of 4 patients: 1 nonsense (Arg554Stop) and 2 missense mutations (Glu354Lys and Ala593Pro) and 1 microdeletion (Leu-608, Val-609) were found. In 3 patients (1 family) with the same phenotypic characteristics, no mutations in the coding sequence of the LH receptor gene were found.

CONCLUSIONS

We conclude that women with LH resistance have spontaneous breast development, primary or secondary amenorrhoea, infertility, elevated serum LH levels and LH/FSH ratio with normal androgen levels and normal or enlarged cystic ovaries. Therefore, in females, primary and secondary sexual characteristics develop independently of LH action. However, LH stimulation is necessary for normal ovarian steroidogenesis and ovulation.

Menstrual disorders and infertility caused by inactivating mutations of the luteinizing hormone receptor gene

OBJECTIVE

To review clinical findings, hormone levels, and DNA analyses in genetic males and females with inactivating mutations of the LH receptor gene.

DESIGN

Review of reported cases.

SETTING

A university hospital.

PATIENT(S)

Genetic males and females with inactivating mutations of the LH receptor gene.

RESULT(S)

The clinical presentation in genetic males ranged from female genitalia to male genitalia with micropenis caused by Leydig cell hypoplasia. Genetic females presented with amenorrhea or oligomenorrhea, enlarged cystic ovaries, and infertility. Both males and females had elevated LH levels and LH/FSH ratios. Sequencing of genomic DNA revealed homozygous or compound heterozygous deletions, nonsense mutations, or missense mutations in the LH receptor gene.

CONCLUSION(S)

This study of patients with inactivating mutations of the LH receptor indicates that in genetic males, the action of hCG and LH is necessary for the normal development of primary and secondary sexual characteristics. In contrast, secondary sexual characteristics develop in genetic females in the absence of LH action, but they fail to ovulate.

A homozygous microdeletion in helix 7 of the luteinizing hormone receptor associated with familial testicular and ovarian resistance is due to both decreased cell surface expression and impaired effector activation by the cell surface receptor

In this report, the genomic DNA was examined from two siblings with gonadal LH resistance. A 46,XY pseudohermaphrodite presented with female external genitalia and his 46,XX sister exhibited menstrual irregularities (oligoamenorrhea) and infertility. Exons 1-11 of the LH receptor (LHR) gene were amplified by the PCR using different sets of intronic primers and were directly sequenced. Sequencing revealed that both individuals carried a deletion of nucleotides 1822-1827, resulting in the deletion of Leu-608 and Val-609 within the seventh transmembrane helix. This mutation was introduced into a recombinant human (h) LHR cDNA. Transfections of 293 cells with hLHR(wt) vs. hLHR(deltaL608,V609) revealed that very little of the mutant receptor was expressed at the cell surface. This was due to both a decrease in the total amount of receptor expressed as well as to an increased intracellular retention of the mutant receptor. In spite of the decreased cell surface expression of the mutant, sufficient amounts were present to allow for assessment of its functions. Equilibrium binding assays showed that the cell surface hLHR(deltaL608,V609) binds hCG with an affinity comparable to that of the wild-type receptor. However, the cells expressing the hLHR(deltaL608,V609) exhibit only a 1.5- to 2.4-fold stimulation of cAMP production in response to hCG. In contrast, cells expressing comparably low levels of hLHR(wt) responded to hCG with 11- to 30-fold increases of cAMP levels. Therefore, the testicular and ovarian unresponsiveness to LH in these patients appears to be due to a mutation of the hLHR gene in which Leu-608 and Val-609 are deleted. As a consequence, the majority of the mutant receptor is retained intracellularly. The small percentage of mutant receptor that is expressed at the cell surface binds hormone normally but is unable to activate Gs.