Premature menopause due to a small deletion in the long arm of the X chromosome: a report of three cases and a review

Genetics of female infertility due to anomalies of the ovary and mullerian ducts

Genetic factors are pivotal in reproductive development and subsequent reproductive processes. If disturbed, infertility can occur. In the female, genetic factors affecting the ovary and the uterus are not uncommon causes of infertility. Terminal deletions on the X long arm and X short arm and X chromosomal mosaicism have long been accepted as causes of premature ovarian failure (POF). Responsible genes on the X have not yet elucidated. Attractive candidate genes for POF also exist on autosomes, and in over a dozen genes molecular perturbations are documented in non-syndromic POF. The most common single-gene cause of POF is premutation carriers for FMR1 (fragile X syndrome). As other candidate genes and additional ethnic groups are interrogated, the proportion of POF cases due to single-gene mutation will increase. Among uterine anomalies, incomplete mullerian fusion is most common. Increased recurrence risks for first-degree relatives confirm a role for genetic factors; interrogation of candidate genes is under way.

Genes governing premature ovarian failure

Premature ovarian failure (POF) is unexplained amenorrhoea (>6 months), increased FSH (>20 IU/l) and LH occurring before 40 years. Several genes are reported as having significance in POF, including genes governing regulation of the hypothalamic-pituitary-ovarian axis, but their role in ovarian physiology is not known. Deletions or translocations in Xq arm have been found to be associated with POF, assuming presence of ovarian-related genes but ovary-related function of these genes is unclear. Several researchers have suggested specific loci on Xq critical region, POF1 and POF2 and genes DIA, FMR1 and FMR2. The understanding of ovarian physiology, its regulation and genes involved is important to explain the causes of POF. Some genes coordinate development of germ cell to primordial stage, e.g. GDF9, BMP15 and NGF, while others regulate development of further stages, such as FSH and LH. Mutation in these genes may lead to female infertility and are likely to be candidate genes for POF. Recently, association between blepharophimosis-ptosis-epicanthus inversus syndrome type 1 and POF has emerged as a possibility. Galactosaemia is also shown to be important in POF due to toxic effects of accumulated galactose or downstream products. Thus, understanding the role of several genes can be used for the appropriate genetic diagnosis, research and in the clinical practice of POF.

A complex mosaicism 45,X/46,X,del(Xq)/46,X,idic(Xq) in a patient with secondary amenorrhea

A complex mosaicism involving the X chromosome was found in a 35-year-old female affected by secondary amenorrhea and short stature. Her karyotype was: 45,X[20]/46,X,del(X)(pter-->q26::qter)[15]/46,X,idic(X)(pter-->q26::q26-->pter)[9]. No cell contained both abnormal X chromosomes. This observation would suggest a possible mechanism underlying the formation of isodicentric chromosomes.

Premature ovarian failure: etiology and prospects

A search of past and current articles on ovarian physiology and premature ovarian failure (POF) using MEDLINE was performed in order to present an overview of clinical manifestations, necessary laboratory investigations, possible etiologies and treatments for POF. POF is defined as gonadal failure before the age of 40 years. Initially, POF was thought to be permanent, but it is now believed that spontaneous remissions and even pregnancies are possible in affected women. In most cases, the etiology of POF remains elusive, but several rare specific causes have been identified. Although the etiology of POF is heterogenic, the treatment principles are the same. Hormone replacement therapy (HRT) is still the cornerstone of treatment. The only proven method of obtaining a pregnancy in patients with POF is fertilization of a donor oocyte. Cryopreservation of oocytes has worked well in animals but awaits refinement before it can be applied routinely to humans with prodromal POF, or to patients before chemotherapy or irradiation in order to save their oocytes for future fertilization. New alternatives to traditional HRT and methods of fertility preservation are under development, but understanding of the basic pathophysiology of POF is necessary for the development and use of innovative treatments.

Ovarian differentiation and gonadal failure

Ovarian failure can result from several different genetic mechanisms-X chromosomal abnormalities, autosomal recessive genes causing various types of XX gonadal dysgenesis, and autosomal dominant genes. The number and precise location of loci on the X are still under investigation, but it is clear that, in aggregate, these genes are responsible for ovarian maintenance, given that monosomy X shows germ cells that undergo accelerated atresia. Despite recent hypotheses, at present there is no evidence for a gene directing primary ovarian differentiation; this process may be constitutive. Phenotypic/karyotypic correlation and limited molecular confirmation have long shown that proximal Xp and proximal Xq contain regions of the most importance to ovarian maintenance. Terminal deletions at Xp11 result in 50% primary amenorrhea and 50% premature ovarian failure or fertility. Deletions at Xq13 usually produce primary amenorrhea. Terminal deletions nearer the telomeres on either Xp of Xq bring about premature ovarian failure more often than complete ovarian failure. The X-linked zinc finger gene (ZFX) and diaphanous 2 Drosophila homologue (DIAPH2) are the only candidate genes for ovarian maintenance that map to the X chromosome. Additional, as yet unidentified, genes along the X chromosome must be involved. The search for these genes in humans is hampered by the lack of candidate genes that map to the X chromosome, the scarcity of patients with fortuitous autosomal translocations, and small pedigrees, which hinder mapping of the loci. In addition, difficulties with human germ cell research also make it challenging to dissect genes important to ovarian development. Autosomal genes also are involved in ovarian differentiation and gonadal failure. Follicle-stimulating hormone receptor and ataxia telangiectasia are examples of autosomal genes known to cause human ovarian failure. Transgenic mouse models point to many other candidate autosomal genes, and sequencing of the human homologues in affected women should lead to the discovery of new genes responsible for human ovarian failure. Identification, functional analysis, and mapping of novel genes specifically expressed in the ovary of mice and women eventually should lead to fruitful dissection of essential genes in mammalian ovarian development and maintenance.

Premature ovarian failure (POF) in Brazilian fragile X carriers

The gynecological and reproductive histories of 193 women from fragile X families were surveyed. Among the 101 carriers of the premutation, 14 experienced premature menopause, contrarily to their 37 fully mutated and 55 noncarrier female relatives. Although premature menopause showed a tendency to cluster in certain fragile X families, as a group, the premutated women experienced menopause earlier than noncarriers. This suggests that premature menopause may be the extreme effect of a spectrum of ovarian anomalies associated with the fragile X premutation.

Premature ovarian failure: an update

OBJECTIVE

To present an overview of potential etiologies, clinical manifestations, and treatment modalities of premature ovarian failure (POF).

DESIGN

A search of past and current articles on basic ovarian physiology and POF with use of MEDLINE. Additional information was obtained from an active study section on POF at the National Institutes of Health. Specific sections of this manuscript summarize the strengths and weaknesses of the possible pathophysiologic processes and management options of POF as they appear in the literature.

RESULT(S)

POF is not an uncommon disorder. Although the etiology remains elusive in most cases, several rare specific causes have been discovered. Although POF was once thought to be permanent, a substantial number of patients experience spontaneous remissions. Because of the association with other autoimmune diseases, close follow-up is recommended in patients with POF. Hormone replacement therapy remains the cornerstone of treatment, and the best chance of achieving a pregnancy is through oocyte donation.

CONCLUSION(S)

An understanding of basic ovarian embryology and physiology will allow clinicians to apply current treatments and develop new innovative therapies for their patients with POF.

Genomic organization and polymorphism of human angiotensin II type 2 receptor: no evidence for its gene mutation in two families of human premature ovarian failure syndrome

Angiotensin II type 2 (AT(2)) receptor is highly expressed in the fetal tissues and decreases rapidly after birth. AT(2) receptor is re-expressed in the adult atretic ovarian follicles. Recently, it has been reported that AT(2) receptor mediates apoptosis. Primarily, we have cloned human AT(2) receptor cDNA and mapped it to the X-chromosome. To further analyze the organization and function of the AT(2) receptor gene, in this study we cloned the human AT(2) receptor genomic DNA. Human AT(2) receptor gene is composed of three exons and two introns. Primer extension analysis revealed a putative transcription initiation site at 24 bp downstream from TATA box. Furthermore, we identified a polymorphism (C-A) in 3' untranslated region of exon 3, which may be a useful genetic marker for genetic analysis of human X-linked inherited disease. In this study, we postulated that the patients with premature ovarian failure, which has been reported to be linked with X-chromosome abnormality, have AT(2) receptor mutation that may contribute to the early onset of atresia. We examined the entire coding sequence of this receptor in two different families of sisters with premature ovarian failure (POF) but found no changes in nucleotide sequences.

Premature ovarian failure and ovarian autoimmunity

Premature ovarian failure (POF) is defined as a syndrome characterized by menopause before the age of 40 yr. The patients suffer from anovulation and hypoestrogenism. Approximately 1% of women will experience menopause before the age of 40 yr. POF is a heterogeneous disorder with a multicausal pathogenesis involving chromosomal, genetic, enzymatic, infectious, and iatrogenic causes. There remains, however, a group of POF patients without a known etiology, the so-called "idiopathic" form. An autoimmune etiology is hypothesized for the POF cases with a concomitant Addison's disease and/or oöphoritis. It is concluded in this review that POF in association with adrenal autoimmunity and/or Addison's disease (2-10% of the idiopathic POF patients) is indeed an autoimmune disease. The following evidence warrants this view: 1) The presence of autoantibodies to steroid-producing cells in these patients; 2) The characterization of shared autoantigens between adrenal and ovarian steroid-producing cells; 3) The histological picture of the ovaries of such cases (lymphoplasmacellular infiltrate around steroid-producing cells); 4) The existence of various autoimmune animal models for this syndrome, which underlines the autoimmune nature of the disease. There is some circumstantial evidence for an autoimmune pathogenesis in idiopathic POF patients in the absence of adrenal autoimmunity or Addison's disease. Arguments in support of this are: 1) The presence of cellular immune abnormalities in this POF patient group reminiscent of endocrine autoimmune diseases such as IDDM, Graves' disease, and Addison's disease; 2) The more than normal association with IDDM and myasthenia gravis. Data on the presence of various ovarian autoantibodies and anti-receptor antibodies in these patients are, however, inconclusive and need further evaluation. A strong argument against an autoimmune pathogenesis of POF in these patients is the nearly absent histological confirmation (the presence of an oöphoritis) in these cases (< 3%). However, in animal models using ZP immunization, similar follicular depletion and fibrosis (as in the POF women) can be detected. Accepting the concept that POF is a heterogenous disorder in which some of the idiopathic forms are based on an abnormal self-recognition by the immune system will lead to new approaches in the treatment of infertility of these patients. There are already a few reports on a successful ovulation-inducing treatment of selected POF patients (those with other autoimmune phenomena) with immunomodulating therapies, such as high dosages of corticosteroids (288-292).

FRAXA premutation associated with premature ovarian failure

A family is described in which six females in three generations experienced premature ovarian failure (POF). In three of them a FRAXA premutation was documented and the carrier status of a fourth female could be inferred, because her son had the fragile X syndrome. These findings provide further evidence for a nonrandom association between POF and the FRAXA premutation.

Predicting age at menopause

This article reviews methodologic and clinical aspects of predicting age at menopause. Lifetable methods or logistic models applied to a perimenopausal population represent the most feasible and the least biased methods for estimating the probability of menopause by age. Information is emerging about risk factors besides age which influence risk for an earlier menopause and include a variety of medical, demographic, environmental, and genetic factors. The concept of menopause as a consequence of depleted oocytes suggests that the estimated number of ovulatory cycles might also be a useful predictor. Using these variables in a logistic model yields estimated probabilities of menopause for various risk profiles. Smokers who have accumulated more than 10 pack-years, women estimated to have had more than 300 ovulatory cycles, women with a history of depression, women who have lost one ovary at an early age, and women who have a family history of early menopause have earlier menopause and the greatest shift in the cumulative probability of menopause occurs in women with multiple risk factors.

Family history as a predictor of early menopause

OBJECTIVE

To determine the relative importance of family history as a predictor of early menopause.

DESIGN

Case-control study. From a population-based survey of 10,606 women between 45 and 54 years of age, we selected 344 cases with early menopause (average age 42.2 years) and 344 age-matched controls who were still menstruating or who had a menopause after age 46 years. Subjects were interviewed about their medical and family history and blood was drawn for identification of women who were carriers for the classic or Duarte variant of galactosemia, a potential hereditary factor for early menopause. Logistic regression analysis was used to estimate the risk of an early menopause in women with and without a family history of early menopause.

RESULTS

Overall 129 (37.5%) of the early menopause cases reported a family history of menopause before age 46 years in a mother, sister, aunt, or grandmother compared to 31 (9.0%) of controls yielding an odds ratio (OR) of 6.1 (95% confidence interval [CI] of 3.9 to 9.4) after adjustment for smoking history, education, parity, and body mass index. Risk for early menopause associated with family history of same was greatest: for family history in a sister, OR = 9.1 (95% CI 3.1 to 26.5); multiple relatives, OR = 12.4 (95% CI 4.4 to 34.2); and cases menopausal before age 40 years, OR = 8.4 (95% CI 2.5 to 31.2). Cases with a family history of early menopause were not more likely to have errors of galactose metabolism compared with cases without a family history or to all controls, nor did they possess Turner's stigmata such as short stature, but they were less likely to have brothers in their sibships.

CONCLUSIONS

Although preferential recall of family history by women with early menopause could contribute to the association between family history and early menopause observed in this study, a genetic factor is also plausible including partial deletions of the X chromosome compatible with the deficiency of male siblings in cases with family history of early menopause.

Deletions of Xq and growth deficit: a review

A critical review of the literature disclosed 44 cases with a 46,X,Xq- karyotype without apparent mosaicism. Of these, 17 were of normal height (compared to the respective population), 11 had a height of over 1 SD below the mean, and 16 had a height of over 2 SD below the mean with breakpoints between Xq13 and Xq25. Since patients of normal height occurred with breakpoints as proximal as Xq13 we conclude that there is no major "growth gene" on Xq distal to q13. The most likely explanation for the variable phenotypic effect of Xq- is to assume that growth gene(s) in Xp or proximal Xq are inactivated on such a chromosome with some variability similar to the variable spreading of X inactivation seen in some X-autosome translocations.

Premature menopause because of an inherited deletion in the long arm of the X-chromosome

A family is described in which both a mother and an infertile daughter had premature menopause at the ages of 31 and 28 years, respectively. Initially, an extensive investigation revealed no apparent cause for their conditions. However, when cytogenetic analysis in the daughter was performed, a terminal deletion in the long arm of one of the X-chromosomes was found. The karyotype was: 46,Xdel(X),(q25-qter). Chromosomal investigation in the mother showed an identical deletion. The karyotype of the patient's 35-year-old sister is normal. She has a normal menstrual cycle and two normal children. The presence of such familial cases suggests that chromosomal investigation should be considered in young women with oligomenorrhea, especially those whose mothers have experienced a premature menopause.

Distal long arm deletions of the X chromosome and ovarian failure

A mother and daughter are described with premature menopause and deletion of the X chromosome at q28.

Chromosome studies and fertility treatment in women with ovarian failure

In vitro fertilization and embryo transfer or gamete (or zygote) intra-Fallopian transfer after ovum donation were performed in 16 patients with primary or secondary amenorrhea, associated with chromosome abnormalities. The patients showed the wide range of (mostly X) chromosome abnormalities characteristic for women with primary or premature ovarian failure. Four of these patients became pregnant and three of them have delivered healthy infants with a normal karyotype. This pregnancy rate is far superior to the accepted fertility figure in these patients. When these results were compared with the fertility treatment results of three other groups of women with absent ovarian function (1. ovarian dysgenesis; 2. surgical castration; 3. premature menopause) but with a normal 46,XX karyotype, no difference in treatment efficiency could be detected. These results offer a promising approach for the treatment of infertility in agonadal patients with chromosome aberrations.

Fertility with deletion Xq25: report of three cases; possible exceptions for critical region hypothesis

We report on an Arab family in which a mother and two of her daughters, despite having deletion Xq25, are fertile. So far, only one case of deletion Xq25 associated with fertility has been reported. Consistent inactivation of the deleted X chromosome in the proposita and early menopause in the mother were noted. The effect of Xq deletion on fertility and the CRH is discussed.

Long arm deletions of the X chromosome and their symptoms: a new case (bp q24) and a short review of the literature

The clinical and cytogenetic data from a 26-year-old female with del(X)(q24----ter) are reported. This breakpoint has not been described yet. Besides this report we give a comparative summary of 24 cases from the literature with different deletions of Xq.

The phenotypic effects of small, distal Xq deletions

The effects of small, distal Xq deletions (Xq26----qter) have been reviewed in light of three cases of our own and five from the literature. The symptoms caused by such deletions range from apparently none through irregular menstruation to secondary amenorrhea (or premature menopause) to primary amenorrhea. That the abnormal chromosome has any effects when it is inactivated may best be explained by one or by a combination of the following hypotheses. (1) the Xq-chromosome might exert an effect during development when cells in which it is active compete with cells in which it is inactivated, assuming that the inactivation of the two X chromosomes is originally random. (2) a more probable hypothesis is that there is a position effect when a break has occurred in the critical region Xq13----q27 which apparently must be intact in both X chromosomes to allow normal development of the ovaries. (3) this position effect might, in turn, affect the oocytes (and thus the ovary) after the inactive X chromosome is reactivated before meiosis or the deletion as such might have a direct effect on the ovaries.

X long-arm deletions. A review of non-mosaic cases studied with banding techniques

A woman with secondary amenorrhoea and an X long-arm deletion (pter----q21:) is described and compared with 30 adult non-mosaic, banded cases. Approximately 50% of the patients had gonadal dysgenesis associated with a higher frequency of short stature and "Turner stigmata" than in women with indication of ovarian activity. It is suggested that preservation of bands Xq26----28 may be decisive for normal ovarian function.

Fertility in patients with X chromosome deletions

Three fertile, non-mosaic patients with partial monosomy of an X-chromosome (two with Xp deletion with breakpoints at Xp1106 and Xp2101, respectively, and one with a del(Xq25)) were found among 12 females with Xp deletion and three with Xq deletion investigated in this laboratory after the advent of banding techniques. Four phenotypically normal children resulted from a total of seven pregnancies in these women. Three of the children were chromosomally normal and one girl presented the same del(Xp) as her mother. The possibility of having genotypically and phenotypically normal offspring should be taken into account in the management and genetic counseling of children and females with X-chromosome deletions.