Galactose-1-phosphate uridyl transferase gene mutations in women with premature ovarian failure

Natural conception: repeated predictions over time

STUDY QUESTION

How can we predict chances of natural conception at various time points in couples diagnosed with unexplained subfertility?

SUMMARY ANSWER

We developed a dynamic prediction model that can make repeated predictions over time for couples with unexplained subfertility that underwent a fertility workup at a fertility clinic.

WHAT IS KNOWN ALREADY

The most frequently used prediction model for natural conception (the 'Hunault model') estimates the probability of natural conception only once per couple, that is, after completion of the fertility workup. This model cannot be used for a second or third time for couples who wish to know their renewed chances after a certain period of expectant management.

STUDY DESIGN, SIZE, DURATION

A prospective cohort studying the long-term follow-up of subfertile couples included in 38 centres in the Netherlands between January 2002 and February 2004. Couples with bilateral tubal occlusion, anovulation or a total motile sperm count <1 × 10⁶ were excluded.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The primary endpoint was time to natural conception, leading to an ongoing pregnancy. Follow-up time was censored at the start of treatment or at the last date of contact. In developing the new dynamic prediction model, we used the same predictors as the Hunault model, i.e. female age, duration of subfertility, female subfertility being primary or secondary, sperm motility and referral status. The performance of the model was evaluated in terms of calibration and discrimination. Additionally, we assessed the utility of the model in terms of the variability of the calculated predictions.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the 4999 couples in the cohort, 1053 (21%) women reached a natural conception leading to an ongoing pregnancy within a mean follow-up of 8 months (5th and 95th percentile: 1-21). Our newly developed dynamic prediction model estimated the median probability of conceiving in the first year after the completion of the fertility workup at 27%. For couples not yet pregnant after half a year, after one year and after one and a half years of expectant management, the median probability of conceiving over the next year was estimated at 20, 15 and 13%, respectively. The model performed fair in an internal validation. The prediction ranges were sufficiently broad to aid in counselling couples for at least two years after their fertility workup.

LIMITATIONS, REASONS FOR CAUTION

The dynamic prediction model needs to be validated in an external population.

WIDER IMPLICATIONS OF THE FINDINGS

This dynamic prediction model allows reassessment of natural conception chances after various periods of unsuccessful expectant management. This gives valuable information to counsel couples with unexplained subfertility that are seen for a fertility workup.

STUDY FUNDING/COMPETING INTERESTS

This study was facilitated by grant 945/12/002 from ZonMW, The Netherlands Organization for Health Research and Development, The Hague, The Netherlands. No competing interests.

Premature ovarian failure from current perspective

Premature ovarian failure (POF) is a syndrome characterised by amenorrhoea, hypoestrogenism and hypergonadotropinism before the age of 40. It is a disorder affecting approximately 1% of women <40 years, 1/1,000 women by the age of 30 and 1/10,000 women by the age of 20. POF is not merely an early menopause. Up to 50% of the patients with POF will have intermittent and unpredictable ovarian function which may persist for some years. Heterogeneity of POF is also reflected by the variety of possible causes, including autoimmunity, toxics, drugs, radiation, infectious as well as genetic defects. HRT remains the cornerstone of treatment and the only proven method of achieving pregnancy in these patients is by ovum donation.

Primary ovarian insufficiency: a more accurate term for premature ovarian failure

Premature ovarian failure (POF) is a disorder with a complicated clinical presentation and course that is poorly defined by its name. A more scientifically accurate term for the disorder is primary ovarian insufficiency (POI), a term that can be appropriately modified to describe the state of ovarian function. In recent years, the known aetiologies of POI have expanded, although the cause of POI in a majority of clinical cases remains undefined. The most common aetiologies should be ruled out clinically including chromosomal abnormalities, fragile X premutations and autoimmune causes. Management should be directed at symptom resolution and bone protection, but most importantly should include psychosocial support for women facing this devastating diagnosis.

Genetic investigation of four meiotic genes in women with premature ovarian failure

OBJECTIVE

The goal of this study was to determine whether mutations of meiotic genes, such as disrupted meiotic cDNA (DMC1), MutS homolog (MSH4), MSH5, and S. cerevisiae homolog (SPO11), were associated with premature ovarian failure (POF).

DESIGN

Case-control study.

METHODS

Blood sampling, karyotype, hormonal dosage, ultrasound, and ovarian biopsy were carried out on most patients. However, the main outcome measure was the sequencing of genomic DNA from peripheral blood samples of 41 women with POF and 36 fertile women (controls).

RESULTS

A single heterozygous missense mutation, substitution of a cytosine residue with thymidine in exon 2 of MSH5, was found in two Caucasian women in whom POF developed at 18 and 36 years of age. This mutation resulted in replacement of a non-polar amino acid (proline) with a polar amino acid (serine) at position 29 (P29S). Neither 36 control women nor 39 other patients with POF possessed this genetic perturbation. Another POF patient of African origin showed a homozygous nucleotide change in the tenth of DMC1 gene that led to an alteration of the amino acid composition of the protein (M200V).

CONCLUSIONS

The symptoms of infertility observed in the DMC1 homozygote mutation carrier and in both patients with a heterozygous substitution in exon 2 of the MSH5 gene provide indirect evidence of the role of genes involved in meiotic recombination in the regulation of ovarian function. MSH5 and DMC1 mutations may be one explanation for POF, albeit uncommon.

Higher frequency of the galactose-1-phosphate uridyl transferase gene K285N mutation in the Slovenian population

OBJECTIVES

To analyze a healthy Slovenian population for the frequency of the classical galactosemia allele K285N.

DESIGN AND METHODS

DNA was analyzed by means of polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

The allele frequency of the K285N mutation in Slovenian population is 0.29%.

CONCLUSIONS

The allele frequency of the K285N mutation in Slovenian population is higher than in other Caucasian populations. K285N is one of the most frequent classical galactosemia mutations in the Slovenian population.

Pathophysiology of impaired ovarian function in galactosaemia

Classical galactosaemia is an inherited inborn error of the major galactose assimilation pathway, caused by galactose-1-phosphate uridyltransferase (GALT) deficiency. Many GALT mutations have been described, with different clinical consequences. In severe forms, newborns present with a life-threatening, acute toxic syndrome that rapidly regresses under a galactose-restricted diet. However, long-term complications, particularly cognitive and motor abnormalities, as well as hypergonadotrophic hypogonadism in female patients are still unavoidable. The pathogenesis of galactose-induced ovarian toxicity remains unclear but probably involves galactose itself and its metabolites such as galactitol and UDP-galactose. Possible mechanisms of ovarian damage include direct toxicity of galactose and metabolites, deficient galactosylation of glycoproteins and glycolipids, oxidative stress and activation of apoptosis. As there is no aetiological treatment, clinical management of ovarian failure in galactosaemic patients principally relies on hormonal replacement therapy to induce pubertal development and to prevent bone loss and other consequences of estrogen deprivation. Further investigations will be necessary to better understand the metabolic flux of galactose through its biochemical pathways and the mechanisms of these secondary complications. The aim of this article is to present an extensive review on the pathogenesis and clinical management of galactose-induced premature ovarian failure.