Coeliac disease and reproductive disorders: a neglected association

Coeliac disease is a chronic disease caused by a permanent intolerance to ingested gluten resulting in immunologically mediated inflammatory damage of the small-intestinal mucosa. The wide spectrum of clinical symptoms is partly due to the malnourished state caused by the malabsorption of macro- and micronutrients. Fertility problems, sexual dysfunction and obstetrical complications are more frequently observed in patients with coeliac disease. These reproductive disorders may be a consequence of the endocrine derangements caused by selective nutrient deficiencies. Nowadays, the early diagnosis and treatment of coeliac disease is possible and not very costly. Therefore, coeliac disease must be seriously considered in the preconceptional screening and treatment of patients with reproductive disorders.

Semen parameters, including WHO and strict criteria morphology, in a fertile and subfertile population: an effort towards standardization of in-vivo thresholds

In this study, the semen analysis results of a fertile population were compared with those from a subfertile population, in order to establish normal cut-off values for the standard semen parameters with the aid of receiver operating characteristic (ROC) curve analysis. The fertile group comprised healthy males (n = 107) without any history of fertility problems, the partners of whom had had a spontaneous pregnancy within one year of unprotected intercourse and were pregnant at the time of the male's inclusion into the study. A total of 103 males from couples attending the infertility clinic, and with an initial sperm count of <20x10(6)/ml were recruited to form the subfertile population. The best discriminating parameter between the two populations was sperm morphology evaluated according to WHO criteria at a cut-off point of 31% normal spermatozoa. The other cut-off values were at 8% for the acrosome index, 45% for motility, and 4% normal spermatozoa for strict criteria. Recalculating the ROC curve cut-off values based on an assumed 50% prevalence of subfertility in an assisted reproductive setting, the cut-off points were reduced to 21% and 3% normal spermatozoa for WHO and strict criteria respectively. For motility, the new cut-off value was at 20% motile spermatozoa, for motility quality at 3.5 (on a scale of 1-6), the acrosome index at 3% normal acrosomes, and the teratozoospermia index at 2.09.

The impact of calcium, magnesium, zinc, and copper in blood and seminal plasma on semen parameters in men

To investigate the impact of calcium, magnesium, zinc, and copper in blood and seminal plasma on semen parameters, 107 fertile and 103 subfertile males provided a standardized blood and semen specimen. Total calcium and magnesium concentrations were determined with colorimetric end point assay procedures. Zinc and copper were determined by flame atomic absorption spectrophotometer (AAS). Semen analysis was performed according to World Health Organization guidelines (1992). The concentrations of calcium, magnesium, zinc, and copper in blood and seminal plasma were not different between the subfertile and fertile group. Weak correlations were demonstrated between blood plasma zinc concentrations and sperm count (rs = 0.18), sperm motility (rs = 0.15), and abnormal sperm morphology (rs = 0.13). Zinc and magnesium concentrations in seminal plasma correlated weakly with sperm count (rs = 0.17 and rs = 0.16, respectively), and copper concentrations in blood plasma with motility (rs = 0.25). Strong correlations were found between calcium, magnesium, and zinc in seminal plasma. Although calcium, magnesium, zinc, and copper play an essential role in spermatogenesis and fertility, the determination of these elements in blood and seminal plasma does not discriminate on the basis of fertility in this group of men.

Longitudinal vitamin and homocysteine levels in normal pregnancy

Evidence of the impact of maternal nutritional status on pregnancy outcome is increasing. However, reference values for vitamin and homocysteine concentrations in maternal blood during normal pregnancy are scarce, and are lacking for the preconceptional period and early pregnancy. Thus, in a longitudinal study we evaluated vitamin and homocysteine concentrations in 102 nulliparous women with an uneventful singleton pregnancy and normal outcome not using supplements. The physiological changes in vitamin and homocysteine concentrations in blood were determined from the preconceptional period throughout pregnancy until 6 weeks post-partum. The vitamins evaluated comprised retinol, thiamin, riboflavin, pyridoxal 5'-phosphate, folate in serum and erythrocytes, vitamin B12 and alpha-tocopherol. The plasma homocysteine concentration was also measured, considering the essential roles of folate, vitamin B6 and vitamin B12 in homocysteine metabolism. The concentrations of retinol, thiamin, pyridoxal 5'-phosphate serum folate and vitamin B12 decreased during pregnancy. In contrast, the concentrations of riboflavin, alpha-tocopherol, and folate in erythrocytes increased or showed only minor changes. Homocysteine concentrations also remained approximately constant during pregnancy. These observations emphasize the importance of preconceptional and post-partum concentrations of vitamins in the evaluation of pregnancy-induced changes. These data have provided valuable reference values for vitamins and homocysteine before, during and after pregnancy in order to contribute to better diagnosis of maternal deficiencies and to study further the relationship between maternal vitamin status and adverse course and outcome of pregnancy.

Folate affects apoptosis in human trophoblastic cells

Effects of folate deficiency on the rate of apoptosis in human cytotrophoblastic cells has been investigated. Apoptosis was determined in cytotrophoblastic cells after culture in 1. control medium, 2. folate-free medium and 3. folate-free medium plus 10% fetal calf serum. Apoptosis rates in cells cultured in mediums 2 and 3 were significantly higher than those cultured in the control medium (P<0.02 and P<0.03, respectively). In conclusion, human cytotrophoblastic cells show a significantly increased rate of apoptosis in vitro after culture in a folate-free medium. Possible explanations for the association between folate deficiency and pregnancy complications are suggested.

Homocysteine metabolism and effects of folic acid supplementation in patients affected with spina bifida

Folic acid supplementation around conception decreases the risk of having offspring with a neural tube defect. However, the aetiology is often still unknown. This study investigated whether spina bifida patients have lower blood folate and higher fasting and post-methionine-load plasma total homocysteine (tHcy) concentrations than control patients. Moreover, the effects of supplementation with 500 microg folic acid/d on folate and tHcy concentrations were determined. Spina bifida patients (n = 12) and disabled control patients (n = 15) received 4 weeks of placebo treatment followed by 4 weeks of intervention with 500 microg folic acid/d. Blood was collected at the start and after 4 and 8 weeks. A methionine-loading test was performed at the start and the end of the study. At baseline, no significant differences occurred between spina bifida and control patients. Folic acid supplementation significantly increased plasma and red blood cell folate concentrations in both groups. Folic acid decreased fasting tHcy concentrations in control patients by 1.6+/-0.5 micromol/l (p<0.01) and in spina bifida patients by 2.2 +/- 1.3 micromol/l (p = 0.10). This study does not show a derangement in homocysteine metabolism in spina bifida compared to control patients. Moreover, folic acid supplementation seems at least as effective in spina bifida patients as in controls.

Cigarette smoking and the risk of male factor subfertility: minor association between cotinine in seminal plasma and semen morphology

OBJECTIVE

To evaluate the impact of cigarette smoking on male factor subfertility and the semen parameters of sperm count, motility, and morphology by questionnaire and determination of the cotinine concentrations in blood and seminal plasma of fertile and subfertile males.

DESIGN

Case-control study of 107 fertile and 103 subfertile males who provided a standardized blood and semen specimen and completed a self-administered questionnaire about their smoking habits.

SETTING

Outpatient fertility clinic of the University Medical Centre St. Radboud, Nijmegen, The Netherlands.

PATIENT(S)

One hundred seven fertile and 103 subfertile males.

INTERVENTION(S)

Vena puncture and semen collection.

MAIN OUTCOME MEASURE(S)

Blood and seminal plasma cotinine levels in relation to semen parameters.

RESULT(S)

A higher frequency of cigarette smoking was observed in subfertile males than in fertile males, with an odds ratio of 1.7 (95% confidence interval, 0.9-3.2). The self-reported number of cigarettes smoked per day correlated with the cotinine concentrations in blood and seminal plasma for both groups. A small but statistically significant correlation was found between cotinine concentrations in seminal plasma and the percentage of abnormal sperm morphology, but not for other semen parameters (r(s) = 0.19).

CONCLUSION(S)

Although the mechanism of the toxicity of cotinine on sperm morphology is not clear, this study indicates only a minor effect of cigarette smoking on male factor subfertility, which is probably due to compounds in cigarette smoke other than nicotine (cotinine).

Low-Dose folic acid supplementation decreases plasma homocysteine concentrations: a randomised trial

An elevated plasma total homocysteine concentration is a risk factor for cardiovascular disease and neural tube defects. A high daily intake of supplemental folic acid is known to decrease total homocysteine concentrations. We studied the effect of low-dose folic acid administration (250 or 500 microg/day for 4 weeks on plasma total homocysteine concentrations and folate status. We also investigated whether total homocysteine concentrations and blood folate concentrations returned to baseline after an 8-week washout period. In this placebo-controlled study, 144 healthy women aged 18-40 years received 500 microg folic acid per day, 500 microg folic acid every second day (250 microg/day), or a placebo tablet with their habitual diet (mean dietary folate intake 280 microg/day). Administration of 250 and 500 microg folic acid per day for four weeks significantly increased folate concentrations in plasma (p<0.001) and red blood cells (p<0.01). Total homocysteine concentrations decreased significantly (p<0.001) in women (n=50) who took 250 microg folic acid daily [mean (+/- SEM) deviation from baseline -11.4 +/-1.98%] and in women (n=45) who took 500 microg folic acid daily (-21.8 +/- 1.49%). Eight weeks after the end of the intervention period (week 12), plasma total homocysteine concentrations in the folic acid-supplemented groups had not returned to baseline (week 0). In conclusion, doses of folic acid as low as 250 microg daily, on an average, in addition to usual dietary intakes of folate, significantly decreased plasma total homocysteine concentrations in healthy, young women. An 8-week washout period was not sufficient for blood folate and plasma total homocysteine concentrations to return to baseline concentration

Evaluation of topical drug treatment in psoriasis

BACKGROUND

During the last decade important innovations in the topical treatment of psoriasis have been accomplished, and important investments in new drug development for psoriasis are planned.

METHODS

A survey was conducted among psoriatic patients in order to quantify the present mode of use of topical drugs by the patients, the mode of prescription by their doctors and the compatibility of actual use and instructions to the patients.

RESULTS

Major observations are: The distribution of lesions, in particular on the scalp and soles, justifies major investments in the development of a treatment at these locations. calcipotriol and topical corticosteroids (classes III and IV) are by far the most frequently prescribed topical drugs. Although at the time of investigation, Calcipotriol was only available as ointment in the Netherlands, it is prescribed twice as often as clobetasol which is both available as an ointment and cream. Dermatologists are responsible for approximately 2/3 and general practitioners for 1/3 of the prescriptions. The prescription by general practitioners also comprises the continuation of prescriptions by the dermatologist. The duration of topical treatment is unrestricted in the majority of patients. However, use of up to 8 weeks is only seldom practised. Therefore, long-term safety and efficacy data of these drugs are mandatory for any topical treatment. Although twice daily treatment was advised in 50% of all patients, this treatment frequency was followed in only 33% of them. Greasiness accounted for non-compliance in 11% of the patients. Less frequent applications were desired by 38% of the patients, including patients on a once-a-day regimen. Most patients preferred the cream formulation. However, the variability of the expression of psoriasis (dry cracked exudative or superficially scaling lesions) required the availability of both cream and ointment formulations.

CONCLUSION

An optimal treatment of psoriasis requires a spectrum of topical drugs and their formulations in different vehicles.

Male factor subfertility: possible causes and the impact of nutritional factors

OBJECTIVE

To review possible causes for male factor subfertility with emphasis on nutritional factors such as zinc and folate.

DESIGN

A literature search was performed on MEDLINE and via bibliographies of published works.

RESULT(S)

Many causes for male factor subfertility are described in the literature. Both environmental and genetic factors could play a role. However, the pathogenesis of male factor infertility is poorly understood, including the role of specific micronutrients such as zinc and folate. Both zinc and folate are involved in the synthesis of DNA and RNA. Despite the fact that zinc deficiency leads to several clinical symptoms such as decreased spermatogenesis and impaired male fertility, the exact pathophysiology has not been clarified.

CONCLUSION(S)

Because most causes of male factor subfertility are unknown, more research is needed. Because male factor subfertility due to nutritional deficiencies is in principle amenable to curative and/or preventive action by supplementation, emphasis should be put on studies on the effect of specific nutrients on male fertility.

Nonsyndromic orofacial clefts: association with maternal hyperhomocysteinemia

Maternal folic acid supplementation has been suggested to play a role in the prevention of nonsyndromic orofacial clefts, i.e., cleft lip +/- cleft palate. Using a case-control design, we investigated vitamin-dependent homocysteine metabolism in 35 mothers with nonsyndromic orofacial cleft offspring and 56 control mothers with nonmalformed offspring. A standardized oral methionine loading test was performed, in which fasting and afterload plasma total homocysteine, serum and red-cell folate, serum vitamin B12, and whole-blood vitamin B6 levels were determined. We found that both fasting (P < 0.01) as well as afterload (P < 0.05) homocysteine concentrations were significantly higher in cases compared to controls. Hyperhomocysteinemia, defined by a fasting and/or afterload homocysteine concentration above the 97.5th percentile, was present in 15.6% of the cases and in 3.6% of controls (odds ratio, 5.3 (1.1-24.2)). The median concentrations of serum (P < 0. 01) and red-cell (P < 0.05) folate were significantly higher, and vitamin B6 concentrations appeared to be significantly lower (P < 0. 05), in cases compared with controls. No significant difference was observed between groups for vitamin B12. These preliminary data offer evidence that maternal hyperhomocysteinemia may be a risk factor for having nonsyndromic orofacial cleft offspring.

Glutathione S-transferase alpha levels in epileptic and healthy women preconceptionally and throughout pregnancy

We studied plasma GSTA1-1 concentrations in preconceptionally recruited epileptic women who received antiepileptic drugs (n = 99) and a control group of healthy women (n = 106). Mean plasma GSTA1-1 concentrations in the control group did not show significant changes preconceptionally and throughout pregnancy. Six weeks postpartum, however, a significant increase in the mean plasma GSTA1-1 concentration (p < 0.001) was found as compared to preconceptional levels and levels during pregnancy. The mean plasma GSTA1-1 concentration in epileptic women was significantly higher in the 4th gestational week compared to those determined in healthy pregnant women (1.68 versus 1.08 microg/l, p < 0.001). Values between the groups in the second and third trimester and postpartum period showed no significant differences.

Bioavailability of lutein from vegetables is 5 times higher than that of beta-carotene

BACKGROUND

To gain more insight into the relation between vegetable consumption and the risk of chronic diseases, it is important to determine the bioavailability of carotenoids from vegetables and the effect of vegetable consumption on selected biomarkers of chronic diseases.

OBJECTIVE

To assess the bioavailability of beta-carotene and lutein from vegetables and the effect of increased vegetable consumption on the ex vivo oxidizability of LDL.

DESIGN

Over 4 wk, 22 healthy adult subjects consumed a high-vegetable diet (490 g/d), 22 consumed a low-vegetable diet (130 g/d), and 10 consumed a low-vegetable diet supplemented with pure beta-carotene (6 mg/d) and lutein (9 mg/d).

RESULTS

Plasma concentrations of vitamin C and carotenoids (ie, alpha-carotene, beta-carotene, lutein, zeaxanthin, and beta-cryptoxanthin) were significantly higher after the high-vegetable diet than after the low-vegetable diet. In addition to an increase in plasma beta-carotene and lutein, the pure carotenoid-supplemented diet induced a significant decrease in plasma lycopene concentration of -0.11 micromol/L (95% CI: -0.21, -0.0061). The responses of plasma beta-carotene and lutein to the high-vegetable diet were 14% and 67%, respectively, of those to the pure carotenoid- supplemented diet. Conversion of beta-carotene to retinol may have attenuated its plasma response compared with that of lutein. There was no significant effect on the resistance of LDL to oxidation ex vivo.

CONCLUSIONS

Increased vegetable consumption enhances plasma vitamin C and carotenoid concentrations, but not resistance of LDL to oxidation. The relative bioavailability of lutein from vegetables is higher than that of beta-carotene.

Low-dose folic acid supplementation does not influence plasma methionine concentrations in young non-pregnant women

An elevated plasma total homocysteine (tHcy) concentration is a risk factor for cardiovascular disease and for having offspring with a neural-tube defect. Folate is a methyl donor in the remethylation of homocysteine into methionine. Although folic acid supplementation decreases tHcy concentrations, effects of folic acid supplementation on plasma methionine concentrations are unclear. There is also concern that folic acid supplementation negatively affects vitamin B12 status. We studied effects of low-dose folic acid supplementation on methionine and vitamin B12 concentrations in plasma. We also investigated whether baseline plasma methionine and tHcy concentrations correlated with the baseline folate and vitamin B12 status. For a period of 4 weeks, 144 young women received either 500 micrograms folic acid each day, or 500 micrograms folic acid and placebo tablets on alternate days, or a placebo tablet each day. Plasma methionine, tHcy and plasma vitamin B12 concentrations were measured at start and end of the intervention period. Folic acid supplementation had no effect on plasma methionine or plasma vitamin B12 concentrations although it significantly decreased tHcy concentrations. Plasma methionine concentrations showed no correlation with either tHcy concentrations (Spearman rs-0.01, P = 0.89), or any of the blood vitamin variables at baseline. Baseline tHcy concentrations showed a slight inverse correlation with baseline concentrations of plasma vitamin B12 (rs-0.25, P < 0.001), plasma folate (rs-0.24, P < 0.01) and erythrocyte folate (rs-0.19, P < 0.05). In conclusion, low-dose folic acid supplementation did not influence plasma methionine or plasma vitamin B12 concentrations. Furthermore, no correlation between plasma methionine concentrations and the blood folate and vitamin B12 status was shown.

Dietary folate from vegetables and citrus fruit decreases plasma homocysteine concentrations in humans in a dietary controlled trial

Elevated total plasma homocysteine (tHcy) concentrations are considered a risk factor for neural tube defects (NTD) and cardiovascular disease. Supplementation with folic acid decreases the risk of women having children with NTD. In both sexes, it decreases tHcy levels. We investigated the efficacy of natural dietary folate in improving folate and homocysteine status. We performed a 4-wk dietary controlled, parallel design intervention trial with 66 healthy subjects (18-45 y) divided into 3 treatment groups: the dietary folate group, the folic acid group and the placebo group. Each day each group was fed a different diet. The dietary folate group received a diet high in vegetables and citrus fruit (total folate content approximately 560 microgram) plus a placebo tablet. The folic acid group received a diet naturally low in folate (approximately 210 microgram) plus 500 microgram folic acid and placebo tablet on alternate days, i.e., 250 microgram folic acid/d. And the placebo group received the same low-folate diet as the folic acid group plus a placebo tablet. After 4 wk of intervention, folate status improved, and tHcy concentrations decreased in both the dietary folate and the folic acid groups. From the amount of additional folate (350 microgram/d) and folic acid (250 microgram/d) consumed, the relative bioavailability of dietary folate compared to folic acid was calculated to be 60-98%, depending on the endpoint used. In conclusion, increasing the consumption of vegetables and citrus fruit, both good sources of folate, will improve folate status and decrease tHcy concentrations. This may contribute to the prevention of cardiovascular disease and NTD in the general population

Low-dose folic acid supplementation decreases plasma homocysteine concentrations: a randomized trial

BACKGROUND

An elevated plasma total homocysteine concentration is a risk factor for cardiovascular disease and neural tube defects. A high daily intake of supplemental folic acid is known to decrease total homocysteine concentrations.

OBJECTIVE

We studied the effect of low-dose folic acid administration (250 or 500 (microgram/d) for 4 wk on plasma total homocysteine concentrations and folate status. We also investigated whether total homocysteine concentrations and blood folate concentrations returned to baseline after an 8-wk washout period.

DESIGN

In this placebo-controlled study, 144 healthy women aged 18-40 y received 500 microgram folic acid/d, 500 microgram folic acid every second day (250 microgram/d), or a placebo tablet with their habitual diet (mean dietary folate intake: 280 microgram/d).

RESULTS

Administration of 250 and 500 microgram folic acid/d for 4 wk significantly increased folate concentrations in plasma (P < 0.001) and red blood cells (P < 0.01). Total homocysteine concentrations decreased significantly (P < 0.001) in women (n = 50) who took 250 microgram folic acid/d [mean (+/-SEM) deviation from baseline: - 11.4 +/- 198%] and in women (n = 45) who took 500 microgram folic acid/d (-21.8 + 1.49%). Eight weeks after the end of the intervention period (week 12), plasma total homocysteine concentrations in the folic acid-supplemented groups had not returned to baseline (week 0).

CONCLUSIONS

Doses of folic acid as low as 250 microgram/d, on average, in addition to usual dietary intakes of folate significantly decreased plasma total homocysteine concentrations in healthy, young women. An 8-wk washout period was not sufficient for blood folate and plasma total homocysteine concentrations to return to baseline concentrations.

[Multiples births: a continuing problem with assisted reproductive techniques]

Assisted reproductive techniques (ART) such as in vitro fertilisation (IVF), ovulation induction and superovulation followed by insemination have caused a sharp increase in multiple birth prevalence rates. The perinatal morbidity of multiple birth infants is high because of the high incidence of premature birth. The social and psychological problems of multiple birth families are also considerable. In 1990 high-order multiple births were mainly the result of IVF. Although the number of IVF treatments has increased more than the number of other ART treatments, nowadays high-order multiple births are predominantly caused by superovulation. Since 1990 the number of high-order multiple births has stabilised, but the recent sharp increase in ART twins results in a further rise in births of severely preterm ART infants. More restraint should be practised in superovulation treatments to bring down the number of (high-order) multiple births.

Multiple birth prevalence in The Netherlands. Impact of maternal age and assisted reproductive techniques

OBJECTIVE

To evaluate the impact of maternal age and use of fertility drugs on multiple birth prevalence from 1970 to 1995 in the Netherlands.

STUDY DESIGN

A population-based survey was carried out in which data were collected from the Centraal Bureau voor Statistiek, the Institute of Medical Statistics and from all clinics for in vitro fertilization.

RESULTS

In the last two decades, the prevalence of multiple births, especially of twin and triplet births, has increased significantly. Three possible explanations for this phenomenon are: (1) introduction of assisted reproductive techniques in combination with fertility drugs; (2) increasing maternal age; and (3) decreasing fecundity with increasing maternal age, resulting in more fertility treatments. A surplus of 1,366 twins was born in 1995 as compared to 1975. The expected excess of twins was 1,368, of which 104 (7.6%) were a result of the increase in total births in 1995, 583 (42.6%) were due to maternal age > 29 years, and, respectively, 330 (24.1%) and 351 (25.7%) twins were due to in vitro fertilization treatment and intrauterine insemination.

CONCLUSION

The delay in achieving pregnancy and the use of fertility-promoting therapies profoundly affect the prevalence of multiple pregnancies in a given country. The general population should be informed of this risk.

Folate intake in Europe: recommended, actual and desired intake

OBJECTIVES

To evaluate possible inconsistencies between recommended, actual and desired folate intake in European adult populations.

DESIGN

Review of dietary recommendations, of food consumption surveys, and of intervention and observational studies relating folate intake to the risk of neural tube defects and plasma homocysteine levels.

RESULTS

In Europe, mean dietary folate intake in adults is 291 micrograms/d (range 197-326) for men and 247 micrograms/d (range 168-320) for women. The recommended intakes vary between 200-300 micrograms/d (men) and 170-300 micrograms/d (women). However, women with a previous pregnancy affected by a neural tube defect (NTD), are recommended to take 4000 micrograms/d of supplemental folic acid when planning a subsequent pregnancy. For those without a history of NTD, the use of 400 micrograms/d of supplemental folic acid is the best option to prevent the occurrence of NTDs. A daily dose of 650 micrograms supplemental folic acid normalises elevated plasma homocysteine levels, which is a risk factor for cardiovascular diseases. A dietary folate intake of at least 350 micrograms/d is desired to prevent an increase in plasma homocysteine levels of the adult population in general.

CONCLUSIONS

Mean dietary folate intake in Europe is in line with recommendations, but the desired dietary intake of > 350 micrograms/d is only reached by a small part of studied European populations. It is considered unethical to investigate whether supplements with a dose lower than 400 micrograms/d of folic acid are also protective against NTDs. However, research to establish the lowest effective dose of dietary folate/supplemental folic acid to optimise homocysteine levels and research on the bioavailability of folate is required. This will enable the choice of a strategy to achieve desired folate intakes in the general population. In the meantime, consumption of plant foods like vegetables, fruits, and cereals should be stimulated to reach the desired level of 350 micrograms of dietary folate per day.

Altered folate and vitamin B12 metabolism in families with spina bifida offspring

Folic acid intake reduces the risk of neural tube defects (NTDs). Although the 677C-->T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene is a risk factor for NTDs, it only partly explains the elevated homocysteine levels in mothers of children with NTDs. We measured vitamin B12, folate and homocysteine in patients with spina bifida (SB), their parents, and in controls, to investigate which other enzymes of homocysteine metabolism might be defective. Because homozygosity for the 677C-->T mutation causes decreased plasma folate and increased red-cell folate (RCF) and plasma homocysteine levels, we excluded individuals homozygous for that mutation. The remaining SB patients and their parents still had lowered plasma folate and elevated total homocysteine levels, and a small subset had decreased vitamin B12 levels. Red-cell folate was the same in all groups, suggesting that dietary folate intake and its uptake was normal. Risk of SB was increased at the 25th percentile of plasma folate and at the 75th percentile of homocysteine values in SB patients and their parents, and at the 5th and 25th percentiles of vitamin B12 in mothers with SB-affected offspring. This underlines the functional importance of homocysteine remethylation to methionine. There was no correlation between vitamin B12 and homocysteine or RCF. In combination with the lowered plasma folate (80-90% 5-methyltetrahydrofolate), our data do not support a major involvement of methionine synthase in the aetiology of SB. Our data rather favour the involvement of genetic variation at loci coding for the formation of 5-methyltetrahydrofolate, such as MTHFR, methylenetetrahydrofolate dehydrogenase or serine hydroxymethyltransferase.

Maternal and fetal levels of methionine and homocysteine in early human pregnancy

OBJECTIVE

To investigate methionine metabolism during normal human embryonic development by measuring levels of methionine and total homocysteine in samples of maternal serum, extra-embryonic coelomic fluid, and amniotic fluid.

DESIGN

Cross-sectional observational study.

SETTING

Collaboration between St Bartholomew's Hospital, London, and the University Hospital of Nijmegen in The Netherlands.

PARTICIPANTS

Twenty-three women with uncomplicated pregnancies between 8 and 12 weeks of gestation before surgical termination of an ultrasonographically normal fetus.

METHODS

Maternal serum samples were collected prior to surgery. Samples of extra-embryonic fluid and amniotic fluids were obtained by transvaginal ultrasound-guided coelocentesis and amniocentesis. Methionine was measured using an amino acid analyser and total homocysteine by high performance liquid chromatography.

RESULTS

Levels of methionine were four times higher in extra-embryonic coelomic fluid and twice as high in amniotic fluid compared with maternal serum. In contrast, the total homocysteine concentrations were much lower in both extra-embryonic coelomic fluid and amniotic fluid than in maternal serum. All differences were significant (P < or = 0.01).

CONCLUSIONS

The comparatively high concentrations of methionine in extra-embryonic coelomic fluid and amniotic fluid, and the concomitant low levels of total homocysteine in these fluids, suggest a role for methionine metabolism during early human pregnancy.

Decreased methylene tetrahydrofolate reductase activity due to the 677C-->T mutation in families with spina bifida offspring

Periconceptional folate intake reduces both the occurrence and recurrence risk of neural tube defects. Plasma homocysteine levels can be elevated in mothers of a child with a neural tube defect, suggesting a dysfunctional folate metabolism. Very recently we showed that a common 677C-->T mutation in the 5,10-methylene tetrahydrofolate reductase gene, causing thermolability of the enzyme, is a risk factor for spina bifida offspring. Restriction enzyme analysis of the genomic 5,10-methylene tetrahydrofolate reductase polymerase chain reaction fragment revealed a significantly higher prevalence of a +/+ genotype among spina bifida patients and their mothers. The risk for spina bifida offspring is the strongest if both the mother and her child have the mutation in the homozygous state. Enzymatic analysis showed that homozygosity for the 677C-->T mutation causes a decreased 5,10-methylene tetrahydrofolate reductase activity, resulting in elevated plasma homocysteine and red blood cell folate levels and lowered plasma folate and cysteine values. This extended study demonstrates that a nucleotide substitution in the coding region of 5,10-methylene tetrahydrofolate reductase, resulting in reduced activity and an impaired homocysteine and folate metabolism, is a genetic risk factor for spina bifida.

Hyperhomocysteinemia: a risk factor for placental abruption or infarction

OBJECTIVE

To establish the prevalence of hyperhomocysteinemia in women with placental abruption or infarction.

DESIGN

Forty-six women with normal pregnancy outcome (controls) and 84 women with placental abruption or infarction (study group) were selected, and studied in the non-pregnant state. Homocysteine metabolism was investigated by a standardized oral methionine loading test. Hyperhomocysteinemia was defined as a concentration of fasting and/or postmethionine plasma homocysteine exceeding the estimated 97.5 percentile level of the controls. In the fasting state, the vitamin status was investigated by the measurement of serum and red cell folate, serum vitamin B12, and whole blood pyridoxal-5'-phosphate (PLP, an active form of vitamin B6).

RESULTS

Hyperhomocysteinemia was diagnosed in four controls (9%) and 26 women of the study group (31%, P < 0.05). The median concentrations of the vitamins studied were significantly lower in women of the study group as compared to the controls, except for red cell folate, where the median concentration was comparable in both groups. The median concentration of fasting plasma homocysteine, unlike post-methionine plasma homocysteine, was significantly higher in women who experienced placental abruption or infarction in their first pregnancy than in women who had the same event after one or more uncomplicated pregnancies.

CONCLUSION

Hyperhomocysteinemia is associated with placental abruption or infarction.

Mutated methylenetetrahydrofolate reductase as a risk factor for spina bifida

Periconceptional folate supplementation reduces the risk of neural-tube defects. We studied the frequency of the 677C-->T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene in 55 patients with spina bifida and parents of such patients (70 mothers, 60 fathers). 5% of 207 controls were homozygous for the 677C-->T mutation compared with 16% of mothers, 10% of fathers, and 13% of patients. The mutation was associated with decreased MTHFR activity, low plasma folate, and high plasma homocysteine and red-cell folate concentrations. The 677C-->T mutation should be regarded as a genetic risk factor for spina bifida.