Biochemical monitoring of pregnancy and breast feeding in five patients with classical galactosaemia--and review of the literature

The hypergonadotropic hypogonadism conundrum of classic galactosemia

BACKGROUND

Hypergonadotropic hypogonadism is a burdensome complication of classic galactosemia (CG), an inborn error of galactose metabolism that invariably affects female patients. Since its recognition in 1979, data have become available regarding the clinical spectrum, and the impact on fertility. Many women have been counseled for infertility and the majority never try to conceive, yet spontaneous pregnancies can occur. Onset and mechanism of damage have not been elucidated, yet new insights at the molecular level are becoming available that might greatly benefit our understanding. Fertility preservation options have expanded, and treatments to mitigate this complication either by directly rescuing the metabolic defect or by influencing the cascade of events are being explored.

OBJECTIVE AND RATIONALE

The aims are to review: the clinical picture and the need to revisit the counseling paradigm; insights into the onset and mechanism of damage at the molecular level; and current treatments to mitigate ovarian damage.

SEARCH METHODS

In addition to the work on this topic by the authors, the PubMed database has been used to search for peer-reviewed articles and reviews using the following terms: 'classic galactosemia', 'gonadal damage', 'primary ovarian insufficiency', 'fertility', 'animal models' and 'fertility preservation' in combination with other keywords related to the subject area. All relevant publications until August 2022 have been critically evaluated and reviewed.

OUTCOMES

A diagnosis of premature ovarian insufficiency (POI) results in a significant psychological burden with a high incidence of depression and anxiety that urges adequate counseling at an early stage, appropriate treatment and timely discussion of fertility preservation options. The cause of POI in CG is unknown, but evidence exists of dysregulation in pathways crucial for folliculogenesis such as phosphatidylinositol 3-kinase/protein kinase B, inositol pathway, mitogen-activated protein kinase, insulin-like growth factor-1 and transforming growth factor-beta signaling. Recent findings from the GalT gene-trapped (GalTKO) mouse model suggest that early molecular changes in 1-month-old ovaries elicit an accelerated growth activation and burnout of primordial follicles, resembling the progressive ovarian failure seen in patients. Although data on safety and efficacy outcomes are still limited, ovarian tissue cryopreservation can be a fertility preservation option. Treatments to overcome the genetic defect, for example nucleic acid therapy such as mRNA or gene therapy, or that influence the cascade of events are being explored at the (pre-)clinical level.

WIDER IMPLICATIONS

Elucidation of the molecular pathways underlying POI of any origin can greatly advance our insight into the pathogenesis and open new treatment avenues. Alterations in these molecular pathways might serve as markers of disease progression and efficiency of new treatment options.

Two consecutive pregnancies in a patient with premature ovarian insufficiency in the course of classic galactosemia and a review of the literature

AIM

To present a case report of a patient with classic galactosemia and the Q188R/K285N GALT mutation, who conceived spontaneously twice despite severe ovarian failure. A review of the literature is included.

MATERIALS AND METHODS

A 20-year-old patient with classic galactosemia and premature ovarian insufficiency (POI) came to our attention. We performed a routine hormonal and ultrasound examination confirming low ovarian reserve. Due to low rates of pregnancies in individuals with POI (5%-10%), we were almost certain of the infeasibility of pregnancy.

RESULTS

Surprisingly, several months after hospitalization, the patient conceived without any medical intervention and less than a year after the first birth she became pregnant again. While reviewing the literature, 90 pregnancies among galactosemic patients were identified.

CONCLUSIONS

Ovarian failure is a long-term diet-independent complication of classic galactosemia, pertaining to about 90% of affected individuals. This case confirms its unpredicted course, as even the presence of unfavorable factors (absence of spontaneous puberty, early diagnosis of POI, undetectable AMH) may not preclude the chance for conception.

Fertility preservation for genetic diseases leading to premature ovarian insufficiency (POI)

PURPOSE

The current review aims to summarize the data available concerning the applicability of fertility preservation techniques to genetic conditions at risk of premature ovarian insufficiency (POI).

METHODS

A literature review through the PubMed Database was carried out.

RESULTS

About 10% of cases of POI is related to genetic diseases. The most frequent conditions associated with POI are Turner syndrome and fragile X pre-mutation; mutation of BRCA 1-2 genes and several other mutations and genetic syndromes have recently been highlighted, although they rarely occur. If a diagnosis is issued before POI onset, counseling on currently available fertility preservation techniques is advisable. In case of spontaneous menarche (this can occur variably depending on the mutation) established techniques like embryo or oocyte cryopreservation can be proposed, even if, in some cases, their effectiveness may be reduced by ovarian alterations connected to the mutation. Ovarian tissue cryopreservation has recently been defined as an established medical procedure for fertility preservation in young cancer patients and may be an option for prepubertal patients. However, it is still experimental in special populations with genetic diseases causing POI. New innovative experimental techniques, like in vitro maturation of immature oocytes (IVM) and vitro activation (IVA) of immature follicles on ovarian tissue, have shown limited but encouraging data and they will be probably available in the near future. For a correct risk-benefit evaluation, the following aspects should be considered: actual knowledge about the pathology-specific efficacy of the various techniques, the average age of onset of POI, the possible risks associated with the procedure in relation to the underlying pathology, the probability of spontaneous conception, as well as the health implications of a possible future pregnancy..

CONCLUSIONS

Fertility preservation techniques represent a crucial opportunity for patients with genetic risk of POI. Early diagnosis increases the chances to apply these techniques. No specific recommendations concerning fertility preservation for each genetic pathology are available, and clinicians should first counsel the patient and her relatives about known risks and benefits of the available techniques, both those established and those considered as experimental.

Nutrition and medical support during pregnancy and lactation in women with inborn errors of intermediary metabolism disorders (IEMDs)

The establishment of expanded newborn screening (NBS) not only results in the early diagnosis and treatment of neonates with inborn errors of intermediary metabolism disorders (IEMDs) but also helps the affected females to reach the reproductive age under medical and dietetic support, as well as to give birth to normal infants. In this review, we aimed to focus on laboratory investigation tests, dietetic management and medical support for most known IEMD pregnant and lactating women, such as those suffering from aminoacidopathies, carbohydrate metabolic diseases and fatty acid (FAO) oxidation disorders.

Primary ovarian insufficiency in classic galactosemia: current understanding and future research opportunities

Classic galactosemia is an inborn error of the metabolism with devastating consequences. Newborn screening has been successful in markedly reducing the acute neonatal symptoms from this disorder. The dramatic response to dietary treatment is one of the major success stories of newborn screening. However, as children with galactosemia achieve adulthood, they face long-term complications. A majority of women with classic galactosemia develop primary ovarian insufficiency and resulting morbidity. The underlying pathophysiology of this complication is not clear. This review focuses on the reproductive issues seen in girls and women with classic galactosemia. Literature on the effects of classic galactosemia on the female reproductive system was reviewed by an extensive Pubmed search (publications from January 1975 to January 2017) using the keywords: galactosemia, ovarian function/dysfunction, primary ovarian insufficiency/failure, FSH, oxidative stress, fertility preservation. In addition, articles cited in the search articles and literature known to the authors was also included in the review. Our understanding of the role of galactose metabolism in the ovary is limited and the pathogenic mechanisms involved in causing primary ovarian insufficiency are unclear. The relative rarity of galactosemia makes it difficult to accumulate data to determine factors defining timing of ovarian dysfunction or treatment/fertility preservation options for this group of women. In this review, we present reproductive challenges faced by women with classic galactosemia, highlight the gaps in our understanding of mechanisms leading to primary ovarian insufficiency in this population, discuss new advances in fertility preservation options, and recommend collaboration between reproductive medicine and metabolic specialists to improve fertility in these women.

Fertility in adult women with classic galactosemia and primary ovarian insufficiency

OBJECTIVE

To study pregnancy chance in adult women with classic galactosemia and primary ovarian insufficiency. Despite dietary treatment, >90% of women with classic galactosemia develop primary ovarian insufficiency, resulting in impaired fertility. For many years, chance of spontaneous conception has not been considered, leading to counseling for infertility. But an increasing number of reports on pregnancies in this group questions whether current counseling approaches are correct.

DESIGN

Multicenter retrospective observational study.

SETTING

Metabolic centers.

PATIENT(S)

Adult women (aged >18 y) with confirmed classic galactosemia and primary ovarian insufficiency were included.

INTERVENTION(S)

Participants and medical records were consulted to obtain study data in a standardized manner with the use of a questionnaire.

MAIN OUTCOME MEASURE(S)

Conception opportunities, time to pregnancy, pregnancy outcome, hormone replacement therapy use, fertility counseling, and the participants' vision of fertility were evaluated. Potential predictive factors for increased pregnancy chance were explored.

RESULT(S)

Eighty-five women with classic galactosemia and primary ovarian insufficiency participated. Twenty-one women actively attempted to conceive or did not take adequate contraceptive precautions. Of these 21 women, nine became pregnant spontaneously (42.9%). This was higher than reported in primary ovarian insufficiency due to other causes (5%-10%). After a period of 12 months, a cumulative proportion of 27.8% of couples had conceived, which increased to 48.4% after 24 months and 61.3% after 27 months. Predictive factors could not be identified. A considerable miscarriage rate of 30% was observed (6 of 20 pregnancies). Although a substantial proportion of women expressed a child-wish (n = 28/53; 52.8%), the vast majority of participants (n = 43/57; 75.4%) considered conceiving to be highly unlikely, owing to negative counseling in the past.

CONCLUSION(S)

The pregnancy rate in women with classic galactosemia and primary ovarian insufficiency was higher than for women with primary ovarian insufficiency of any cause. This shifting paradigm carries significant implications for fertility counseling and potential application of fertility preservation techniques.

Spontaneous Recovery of Ovarian Function in an Adolescent with Galactosemia and Apparent Premature Ovarian Insufficiency

BACKGROUND

Galactosemia is an inborn error of metabolism resulting in premature ovarian insufficiency in 80-90% of females. There have been no reported cases of biochemical ovarian failure followed by normal menses.

CASE

A 12-year-old girl with galactosemia presented for gynecologic consultation. Her follicle-stimulating hormone (FSH) and estradiol levels were 52.9 U/L and less than 100 pmol/L, respectively. She started exogenous estrogen to stimulate puberty. At 16, she had spontaneous regular menstrual cycles. FSH and luteinizing hormone (LH) levels reflected normal ovarian function. Hormonal contraception was provided. One year later, she was found to be in ovarian failure (FSH 86.6 U/L, LH 33.3 U/L), and both estradiol and anti-Müllerian hormone were undetectable.

SUMMARY AND CONCLUSIONS

This case documents spontaneous resumption of ovarian function after galactosemia-related ovarian failure. The use of FSH and LH is potentially limited in predicting ovarian function in this population.

Fertility preservation in female classic galactosemia patients

Almost every female classic galactosemia patient develops primary ovarian insufficiency (POI) as a diet-independent complication of the disease. This is a major concern for patients and their parents, and physicians are often asked about possible options to preserve fertility. Unfortunately, there are no recommendations on fertility preservation in this group. The unique pathophysiology of classic galactosemia with a severely reduced follicle pool at an early age requires an adjusted approach. In this article recommendations for physicians based on current knowledge concerning galactosemia and fertility preservation are made. Fertility preservation is only likely to be successful in very young prepubertal patients. In this group, cryopreservation of ovarian tissue is currently the only available technique. However, this technique is not ready for clinical application, it is considered experimental and reduces the ovarian reserve. Fertility preservation at an early age also raises ethical questions that should be taken into account. In addition, spontaneous conception despite POI is well described in classic galactosemia. The uncertainty surrounding fertility preservation and the significant chance of spontaneous pregnancy warrant counseling towards conservative application of these techniques. We propose that fertility preservation should only be offered with appropriate institutional research ethics approval to classic galactosemia girls at a young prepubertal age.

Sensitive measurement of polyols in urine by capillary zone electrophoresis coupled with amperometric detection using on-column complexation with borate

Little is known about human polyol metabolism, but recent studies indicate that abnormal polyol concentrations in body fluids are related to several diseases. In this study, a rapid and sensitive method for the determination of seven major polyols in urine including two groups of polyol isomers, C5-polyols (Rib+Arb+Xyl) and C6-polyols (Sor+Gal+Man), was developed using capillary zone electrophoresis coupled with amperometric detection (CZE-AD). The effects of the working electrode potential, pH, running buffer components and concentrations, separation voltage and injection times were investigated. Under the optimised conditions, seven types of polyols could be perfectly separated via the formation of anionic polyol-borate complexes in a borate buffer solution. Highly linear current responses to the polyol concentrations were obtained with good correlation (0.9984<R(2)<0.9997), and the limits of detection (LODs) ranged from 1.33×10(-6) to 5.8×10(-7) mol L(-1) (S/N=3). The proposed method has been successfully used to detect polyols in urinary samples from healthy subjects and diabetes patients, demonstrating accurate and reliable results. This method has potential applications in the recognition of inborn errors affecting polyol metabolism.

Ovarian function in girls and women with GALT-deficiency galactosemia

Primary or premature ovarian insufficiency (POI) is the most common long-term complication experienced by girls and women with classic galactosemia; more than 80% and perhaps more than 90% are affected despite neonatal diagnosis and careful lifelong dietary restriction of galactose. In this review we explore the complexities of timing and detection of galactosemia-associated POI and discuss potential underlying mechanisms. Finally, we offer recommendations for follow-up care with current options for intervention.

Ovarian tissue cryopreservation and subsequent spontaneous pregnancies in a patient with classic galactosemia

OBJECTIVE

To report two consecutive spontaneous pregnancies in a compound heterozygous patient with classic galactosemia and a heterozygous partner, 6 years after ovarian tissue cryopreservation.

DESIGN

Case report.

SETTING

Tertiary health care center.

PATIENT(S)

A patient with classic galactosemia and strict adherance to a galactose-free diet.

INTERVENTION(S)

Right ovariectomy by laparoscopy and cryopreservation of cortical slices; metabolic follow-up.

MAIN OUTCOME MEASURE(S)

Genotyping, galactose-1-phosphate uridyltransferase (GALT) activity and erythrocyte galactose-1-phosphate determination, histology of ovarian cortex, pregnancy achievement.

RESULT(S)

Undetectable GALT activity; compound heterozygosity: association of c.563A>G (p.Gln188Arg) and a novel mutation c.982C>T (p.Arg328Cys); rare growing follicles and abnormally low primordial follicles; two uneventful spontaneous pregnancies without need for autografting of the cryopreserved tissue.

CONCLUSION(S)

The risk for ovarian failure is a frequent concern, but spontaneous pregnancies may occur, even repeatedly, in young patients with galactosemia. Thus, there is a need for more accurate predictive factors to guide the indication for ovarian tissue cryopreservation, the benefits and risks of which have to be balanced through a multidisciplinary approach.

Galactose toxicity in animals

In most organisms, productive utilization of galactose requires the highly conserved Leloir pathway of galactose metabolism. Yet, if this metabolic pathway is perturbed due to congenital deficiencies of the three associated enzymes, or an overwhelming presence of galactose, this monosaccharide which is abundantly present in milk and many non-dairy foodstuffs, will become highly toxic to humans and animals. Despite more than four decades of intense research, little is known about the molecular mechanisms of galactose toxicity in human patients and animal models. In this contemporary review, we take a unique approach to present an overview of galactose toxicity resulting from the three known congenital disorders of galactose metabolism and from experimental hypergalactosemia. Additionally, we update the reader about research progress on animal models, as well as advances in clinical management and therapies of these disorders.

Pregnancy in classic galactosemia despite undetectable anti-Müllerian hormone

OBJECTIVE

To report a pregnancy in a patient with classic galactosemia despite signs of no ovarian reserve to draw attention to the limited predictive value of ovarian reserve tests in these patients.

DESIGN

Case report.

SETTING

Secondary and tertiary care center.

PATIENT(S)

A patient with classic galactosemia with premature ovarian failure and two previous pregnancies.

INTERVENTION(S)

Exogenous FSH ovarian reserve test and anti-Müllerian hormone (AMH) measurement.

MAIN OUTCOME MEASURE(S)

17beta-Estradiol response, AMH level.

RESULT(S)

Pregnancy despite undetectable AMH (<0.1 microg/L) and no E(2) response (exogenous FSH ovarian reserve test).

CONCLUSION(S)

Fluctuating premature ovarian failure makes fertility counseling of patients with classic galactosemia difficult. Commonly used ovarian function and reserve tests seem to have no significance.