Immune and spermatogenesis-related loci are involved in the development of extreme patterns of male infertility.

We conducted a genome-wide association study in a large population of infertile men due to unexplained spermatogenic failure (SPGF). More than seven million genetic variants were analysed in 1,274 SPGF cases and 1,951 unaffected controls from two independent European cohorts. Two genomic regions were associated with the most severe histological pattern of SPGF, defined by Sertoli cell-only (SCO) phenotype, namely the MHC class II gene HLA-DRB1 (rs1136759, P = 1.32E-08, OR = 1.80) and an upstream locus of VRK1 (rs115054029, P = 4.24E-08, OR = 3.14), which encodes a protein kinase involved in the regulation of spermatogenesis. The SCO-associated rs1136759 allele (G) determines a serine in the position 13 of the HLA-DRß1 molecule located in the antigen-binding pocket. Overall, our data support the notion of unexplained SPGF as a complex trait influenced by common variation in the genome, with the SCO phenotype likely representing an immune-mediated condition.

Common Variation in the PIN1 Locus Increases the Genetic Risk to Suffer from Sertoli Cell-Only Syndrome.

We aimed to analyze the role of the common genetic variants located in the PIN1 locus, a relevant prolyl isomerase required to control the proliferation of spermatogonial stem cells and the integrity of the blood-testis barrier, in the genetic risk of developing male infertility due to a severe spermatogenic failure (SPGF). Genotyping was performed using TaqMan genotyping assays for three PIN1 taggers (rs2287839, rs2233678 and rs62105751). The study cohort included 715 males diagnosed with SPGF and classified as suffering from non-obstructive azoospermia (NOA, n = 505) or severe oligospermia (SO, n = 210), and 1058 controls from the Iberian Peninsula. The allelic frequency differences between cases and controls were analyzed by the means of logistic regression models. A subtype specific genetic association with the subset of NOA patients classified as suffering from the Sertoli cell-only (SCO) syndrome was observed with the minor alleles showing strong risk effects for this subset (ORaddrs2287839 = 1.85 (1.17-2.93), ORaddrs2233678 = 1.62 (1.11-2.36), ORaddrs62105751 = 1.43 (1.06-1.93)). The causal variants were predicted to affect the binding of key transcription factors and to produce an altered PIN1 gene expression and isoform balance. In conclusion, common non-coding single-nucleotide polymorphisms located in PIN1 increase the genetic risk to develop SCO.

Contribution of TEX15 genetic variants to the risk of developing severe non-obstructive oligozoospermia.

Background: Severe spermatogenic failure (SPGF) represents one of the most relevant causes of male infertility. This pathological condition can lead to extreme abnormalities in the seminal sperm count, such as severe oligozoospermia (SO) or non-obstructive azoospermia (NOA). Most cases of SPGF have an unknown aetiology, and it is known that this idiopathic form of male infertility represents a complex condition. In this study, we aimed to evaluate whether common genetic variation in TEX15, which encodes a key player in spermatogenesis, is involved in the susceptibility to idiopathic SPGF. Materials and Methods: We designed a genetic association study comprising a total of 727 SPGF cases (including 527 NOA and 200 SO) and 1,058 unaffected men from the Iberian Peninsula. Following a tagging strategy, three tag single-nucleotide polymorphisms (SNPs) of TEX15 (rs1362912, rs323342, and rs323346) were selected for genotyping using TaqMan probes. Case-control association tests were then performed by logistic regression models. In silico analyses were also carried out to shed light into the putative functional implications of the studied variants. Results: A significant increase in TEX15-rs1362912 minor allele frequency (MAF) was observed in the group of SO patients (MAF = 0.0842) compared to either the control cohort (MAF = 0.0468, OR = 1.90, p = 7.47E-03) or the NOA group (MAF = 0.0472, OR = 1.83, p = 1.23E-02). The genotype distribution of the SO population was also different from those of both control (p = 1.14E-02) and NOA groups (p = 4.33-02). The analysis of functional annotations of the human genome suggested that the effect of the SO-associated TEX15 variants is likely exerted by alteration of the binding affinity of crucial transcription factors for spermatogenesis. Conclusion: Our results suggest that common variation in TEX15 is involved in the genetic predisposition to SO, thus supporting the notion of idiopathic SPGF as a complex trait.

Intronic variation of the SOHLH2 gene confers risk to male reproductive impairment.

OBJECTIVE: To evaluate whether SOHLH2 intronic variation contributes to the genetic predisposition to male infertility traits, including severe oligospermia (SO) and different nonobstructive azoospermia (NOA) clinical phenotypes. DESIGN: Genetic association study. SETTING: Not applicable. PATIENT(S): Five hundred five cases (455 infertile patients diagnosed with NOA and 50 with SO) and 1,050 healthy controls from Spain and Portugal. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Genomic DNA extraction from peripheral blood mononuclear cells, genotyping of the SOHLH2 polymorphisms rs1328626 and rs6563386 using the TaqMan allelic discrimination technology, case-control association analyses using logistic regression models, and exploration of functional annotations in publicly available databases. RESULT(S): Evidence of association was observed for both rs6563386 with SO and rs1328626 with unsuccessful sperm retrieval after testicular sperm extraction (TESE-) in the context of NOA. A dominant effect of the minor alleles was suggested in both associations, either when the subset of patients with the manifestation were compared against the control group (rs6563386/SO: P=.021, odds ratio [OR] = 0.51; rs1328626/TESE-: P=.066, OR = 1.46) or against the group of patients without the manifestation (rs6563386/SO: P=.014, OR = 0.46; rs1328626/TESE-: P=.012, OR = 2.43). The haplotype tests suggested a combined effect of both polymorphisms. In silico analyses evidenced that this effect could be due to alteration of the isoform population. CONCLUSION(S): Our data suggest that intronic variation of SOHLH2 is associated with spermatogenic failure. The genetic effect is likely caused by different haplotypes of rs6563386 and rs1328626, which may predispose to SO or TESE- depending on the specific allelic combination.

Evaluation of Male Fertility-Associated Loci in a European Population of Patients with Severe Spermatogenic Impairment.

Infertility is a growing concern in developed societies. Two extreme phenotypes of male infertility are non-obstructive azoospermia (NOA) and severe oligospermia (SO), which are characterized by severe spermatogenic failure (SpF). We designed a genetic association study comprising 725 Iberian infertile men as a consequence of SpF and 1058 unaffected controls to evaluate whether five single-nucleotide polymorphisms (SNPs), previously associated with reduced fertility in Hutterites, are also involved in the genetic susceptibility to idiopathic SpF and specific clinical entities. A significant difference in the allele frequencies of USP8-rs7174015 was observed under the recessive model between the NOA group and both the control group (p = 0.0226, OR = 1.33) and the SO group (p = 0.0048, OR = 1.78). Other genetic associations for EPSTI1-rs12870438 and PSAT1-rs7867029 with SO and between TUSC1-rs10966811 and testicular sperm extraction (TESE) success in the context of NOA were observed. In silico analysis of functional annotations demonstrated cis-eQTL effects of such SNPs likely due to the modification of binding motif sites for relevant transcription factors of the spermatogenic process. The findings reported here shed light on the molecular mechanisms leading to severe phenotypes of idiopathic male infertility, and may help to better understand the contribution of the common genetic variation to the development of these conditions.

Cumulative live birth rate after two single frozen embryo transfers (eSFET) versus a double frozen embryo transfer (DFET) with cleavage stage embryos: a retrospective cohort study.

PURPOSE: According to the latest ART report for Europe, about 13% of pregnancies after frozen embryo transfer are multiple. Our objective was to analyse the impact on the multiple pregnancy rate of two eSFET (elective single frozen embryo transfers) versus a DFET (double frozen embryo transfer) in women aged under 38 years, who had not achieved pregnancy in their fresh transfer and who had at least two vitrified embryos of A/B quality. METHODS: This study was conducted from January 2010 to June 2013 at a public hospital. The couples were divided into three groups. Group DFET: the first cryotransfer of two embryos (105 women); cSFET group: the only cryotransfer of a single vitrified embryo (60 women); eSFET group, individually vitrified embryos: 20 patients included in a clinical trial of single-embryo fresh and frozen transfer and 21 patients who chose to receive eSFET. RESULTS: The clinical pregnancy rate was 38.1% in the DET group and the cumulative clinical pregnancy rate was 43.3% in the eSFET group. There were no significant differences between the DFET and eSFET groups (30.0 vs 34.1%) in cumulative live birth delivery rate. The rate of multiple pregnancies varied significantly between the DFET and eSFET groups (32.5 vs 0%, p < 0.05). CONCLUSIONS: For good-prognosis women aged under 38 years, taking embryo quality as a criterion for inclusion, an eSFET policy can be applied, achieving acceptable cumulative clinical pregnancy and live birth rates and reducing multiple pregnancy rates.

Embryologists' health: a nationwide online questionnaire.

PURPOSE: The present study evaluates health status and its relation with occupational characteristics and with burnout syndrome among embryologists. METHODS: A cross-sectional design was used to conduct an online self-assessment survey, sent to all members of the Spanish Association of Clinical Embryologists. The questionnaire contained occupational questions and two standard instruments: 'Short Form-12 Health Survey' as a measure of physical (PCS-12) and mental (MCS-12) health and the Maslach Burnout Inventory-General Survey (MBI-GS) to evaluate the degree of burnout. RESULTS: The PCS-12 obtained for the Spanish embryologists was higher than that for the reference population. However, the total MCS-12 was significantly lower than that observed in non-institutionalised males and females representative of the general Spanish population aged 35-44 years. In the linear regression model, the dependent variable PCS-12 was related indirectly with the variables number of hours worked per week, BMI, back pain, leg pain and visual discomfort. In the linear regression model, the dependent variable MCS-12 was indirectly related to the gender (male reference; female coefficient regression: -3.23), exhaustion and cynicism dimensions of the MBI-GS. A total of 87 (36.3%) embryologists presented a high score on at least one of the MBI-GS dimensions. CONCLUSION: In this sample of Spanish embryologists, a norm measure (SF-12) showed their physical health to be better than the average for the general population, but that their mental health was poorer. A significant indirect relation was observed between mental health and burnout syndrome. Strategies to reduce occupational stress and problems should form part of the training provided for clinical embryologists.

Adherence to reporting guidelines in observational studies concerning exposure to persistent organic pollutants and effects on semen parameters.

STUDY QUESTION: Are studies on semen quality in men exposed to persistent pesticides reported according to the 'strengthening the reporting of observational studies in epidemiology' (STROBE) recommendations and the guidelines for the appraisal of semen quality studies (SEMQUA)? SUMMARY ANSWER: Most studies of the impact of pesticides on semen quality do not follow the STROBE and SEMQUA guidelines, thus adherence is low, especially in methodological aspects. WHAT IS KNOWN ALREADY: Much of the controversy about reduced semen quality in recent decades arises from a lack of standardization in the methodology applied, despite the existence of several validated instruments for evaluating the quality of reporting. Indeed, SEMQUA was purpose-designed for the particular characteristics of semen quality studies. STUDY DESIGN, SIZE, DURATION: A structured literature search identified eligible articles reporting on persistent pesticides and human semen quality, published in English before 1 September 2012. Opinion articles and reviews were excluded. We assessed the adherence to reporting guidelines of the articles, using and comparing the STROBE statement and the SEMQUA guidelines, in both cases with indicators relevant to observational studies of semen quality. PARTICIPANTS/MATERIALS, SETTING, METHODS: A comprehensive bibliographic search in various electronic literature databases using the key words 'sperm' and 'pesticide' obtained 1179 papers, of which 46 were valid for our purposes. The papers examined occupational (26) and environmental exposure (20). Two of the present authors independently piloted the data extraction form for this review. The articles were then evaluated by two researchers using the STROBE and SEMQUA checklists. MAIN RESULTS AND THE ROLE OF CHANGE: Although no significant differences were found between the overall degree of compliance with STROBE and SEMQUA (47.0 ± 18.5% versus 43.1 ± 11.6%), there were significant differences when only methodological aspects were considered (48.4 ± 21.0% versus 39.5 ± 17.4%; P < 0.001). We observed an increase over time in the degree of compliance, for SEMQUA (r = 0.61 and P < 0.001) and STROBE (r = 0.45 and P < 0.01). The papers that reported a negative effect of exposure to persistent pesticides on sperm concentration presented a lower level of compliance to SEMQUA (42.1 ± 18.3% versus 57.6 ± 14.2%; P < 0.01) and STROBE (40.2 ± 10.3% versus 49.5 ± 11.6%; P < 0.05) than those which recorded no such influence. The year of publication and the observed effect on sperm concentration were the only candidate variables included in the model of stepwise multiple regression model for the 'degree of compliance' variables of SEMQUA and STROBE. LIMITATIONS, REASONS FOR CAUTION: Other characteristics of reporting quality, such as legibility, were not evaluated. WIDER IMPLICATIONS OF THE FINDINGS: The low degree of compliance observed is consistent with that observed in other studies of reproductive medicine and highlights the need to improve the design of studies of semen quality. SEMQUA proved to be a more specific tool than STROBE for the field of semen quality. Editors, reviewers and authors should be aware of SEMQUA and apply it when assessing papers on semen quality. STUDY FUNDING/COMPETING INTEREST(S): No research funding was received and none of the authors have any conflict of interests.

Genetic testing of sperm donors for cystic fibrosis and spinal muscular atrophy: evaluation of clinical utility.

OBJECTIVE: To evaluate the clinical utility of genetic testing for cystic fibrosis (CF) and spinal muscular atrophy (SMA) in sperm donors. STUDY DESIGN: We studied the results of the genetic tests for CF and SMA applied to 372 sperm donor candidates. The CF carrier screening test analysed 32 mutations on the CFTR gene. Regarding SMA, the carrier test studied possible deletions of SMN1/2 by Multiplex Ligation-dependent Probe Amplification (MLPA) methodology. RESULTS: The carrier frequency obtained was greater for SMA than for CF. After adjusting the results obtained for the sensitivity of the tests, and taking into account the prevalence of female carriers in our population, the probability of transmission of the disease to the child from a donor with a negative genetic test was about five times lower in the case of SMA than in CF, although this difference was not statistically significant. The number of donors needed to screen (NNS) to avoid the occurrence of a child being affected by CF and SMA in our population was similar in both cases (1591 vs. 1536). CONCLUSIONS: This study demonstrates the need to include SMA among the diseases for which genetic screening is performed in the process of sperm donor selection. We believe that testing donors for SMA is as important and as useful as doing so for CF.

Acceptable variability in external quality assessment programmes for basic semen analysis.

BACKGROUND: External quality assessment is essential in modern andrology laboratories. To assess the proficiency of laboratories participating in an external quality assessment programme (EQAP), limits for acceptable variability must be determined. Limits currently specified largely depend on criteria set by the organizers of individual EQAP schemes. The objective of this study was to evaluate the different criteria described in ISO 13528: 2005 for calculating acceptable variability in EQAP when applied to basic semen analysis parameters. METHODS AND RESULTS: The data used in this study were the means and standard deviations obtained for independent samples from two EQAPs, one national (Spanish) and one international (European). The acceptable variability according to ISO 13528: 2005 was calculated using four types of criteria: (i) ± 3 standard deviations of the results of all participating laboratories; (ii) ± 3 standard deviations of the results of expert laboratories; (iii) quality specifications based on biological variability, state-of-the-art and clinicians' opinions and (iv) the same quality specifications adjusted for the uncertainty of the assigned value. The first two strategies resulted in very wide ranges of acceptable variability. Conversely, the strategy based only on quality specifications resulted in very narrow ranges. For the fourth strategy, acceptable ranges were intermediate between the results produced with the other strategies. The third and fourth strategies did not produce observable differences in acceptable ranges when the model used for calculating the specifications of analytical quality was changed. CONCLUSIONS: It is essential that EQAPs for semen parameters should determine the ranges for acceptable variability in results. Moreover, these ranges must be clinically useful, i.e. the variability should have a minimal negative impact on clinical decisions. The exact definition of 'expert laboratory' is more important than the model chosen for estimating analytical quality specifications in an EQAP for semen parameters in basic semen analysis.

Aplicación de las especificaciones de calidad analíticas al cálculo de los límites admisibles de error en Programas de Evaluación Externa de la Calidad para concentración espermática / Application of the analytical quality specifications to the calculation of the allowable limits of error in Programs of External Quality Assessment for sperm concentration

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PGS-FISH in reproductive medicine and perspective directions for improvement: a systematic review.

INTRODUCTION: Embryo selection can be carried out via morphological criteria or by using genetic studies based on Preimplantation Genetic Screening. In the present study, we evaluate the clinical validity of Preimplantation Genetic Screening with fluorescence in situ hybridization (PGS-FISH) compared with morphological embryo criteria. MATERIAL AND METHODS: A systematic review was made of the bibliography, with the following goals: firstly, to determine the prevalence of embryo chromosome alteration in clinical situations in which the PGS-FISH technique has been used; secondly, to calculate the statistics of diagnostic efficiency (negative Likelihood Ratio), using 2 × 2 tables, derived from PGS-FISH. The results obtained were compared with those obtained from embryo morphology. We calculated the probability of transferring at least one chromosome-normal embryo when it was selected using either morphological criteria or PGS-FISH, and considered what diagnostic performance should be expected of an embryo selection test with respect to achieving greater clinical validity than that obtained from embryo morphology. RESULTS: After an embryo morphology selection that produced a negative result (normal morphology), the likelihood of embryo aneuploidies was found to range from a pre-test value of 65% (prevalence of embryo chromosome alteration registered in all the study groups) to a post-test value of 55% (Confidence interval: 50-61), while after PGS-FISH with a negative result (euploid), the post-test probability was 42% (Confidence interval: 35-49) (p < 0.05). The probability of transferring at least one euploid embryo was the same whether 3 embryos were selected according to morphological criteria or whether 2, selected by PGS-FISH, were transferred. Any embryo selection test, if it is to provide greater clinical validity than embryo morphology, must present a LR-value of 0.40 (Confidence interval: 0.32-0.51) in single embryo transfer, and 0.06 (CI: 0.05-0.07) in double embryo transfer. DISCUSSION: With currently available technology, and taking into account the number of embryos to be transferred, the clinical validity of PGS-FISH, although superior to that of morphological criteria, does not appear to be clinically relevant.

Sperm chromatin structure assay and classical semen parameters: systematic review.

The present study is based on a PubMed search and compares the clinical validity of classical semen parameters (CSP) and the sperm chromatin structure assay (SCSA) in different clinical contexts. The PubMed database was searched using keywords on the sperm diagnostic test for pregnancy in three clinical scenarios: (i) couples attempting to conceive; (ii) couples who had been attempting to conceive for 12months without success; and (iii) couples treated with intrauterine insemination (IUI). There was a considerable heterogeneity among the studies included. For couples attempting to conceive following a SCSA that produced an abnormal result, the likelihood of male factor infertility ranged from a pre-test value of 7.5% to a post-test value of 32.1% [95% confidence interval (CI) 15.7-54.5], while after CSP with an abnormal result, the post-test probability was 17.3% (95% CI 11.8-24.5). For a pre-test prevalence of male factor infertility of 50%, the post-test probability of male factor infertility after an abnormal test is very similar for both SCSA and CSP. In couples treated with IUI, the clinical validity of SCSA is higher than that of sperm morphology alone, but not enough to introduce SCSA as a test in male infertility work-up.

Comparison of methods to determine the assigned value in an external quality control programme for embryo evaluation.

This study set out to establish adequate assigned values for a National External Quality Control Programme of embryo evaluation. The results obtained by Spanish laboratories in this programme are compared with those of a group of national experts in embryo quality. Image-based embryo evaluation consists not only of classifying embryos as being of optimal, moderate or poor quality, but also of specifying the clinical decision to be taken regarding each embryo (transfer, cryopreservation or rejection). The proportion of embryos for which there was a high degree of agreement among the experts was 98.3% for embryo classification and 93.3% for clinical decision; for the laboratories, the respective values were 44.2 and 42.5%. With respect to the interobserver agreement among laboratories and experts, kappa coefficients were lower than 0.6 both for classification and for clinical decision. The experts recommended cryopreservation of a higher percentage of embryos classified as poor quality than did the laboratories (28 versus 4%, P = 0.05). The data obtained show that the agreement among laboratories is lower than among experts, and that the concordance among experts and laboratories is moderate. Therefore, it is recommended that an assigned value from external quality control programmes is established based on the consensus values obtained from experts.

El dopaje en atención primaria / Doping at primary care

El médico de Atención Primaria se enfrenta día adía a variedad de patologías y de personas, cada una con circunstancias distintas. En este artículo se intenta hacer una revisión de conceptos sobre el doping en el deporte enfocada a los médicos de Atención Primaria, puesto que muchas veces acuden a consulta personas deportistas y debemos tener en cuenta todo lo que puede supone el consumo de los fármacos que recomendamos, cuáles podemos prescribir y qué debemos de hacer si es absolutamente el consumo de alguna sustancia farmacológica durante el desarrollo de una prueba deportiva. Se hace también un repaso a las causas por las que se dopan y características que nos deben poner en alerta sobre un posible dopaje, además de la conducta y consejos a tener en cuenta con los deportistas en nuestras consultas (AU)

The doctor of Primary Care faces to variety of pathologies and people, each one with different circumstances. In this article it is tried to make a revision of concepts on doping in the sport focused to the doctors of Primary Care, since often sport people go to consultation and we must consider everything what can supposes the consumption of the drugs that we recommended, which we can prescribe and what we must do if it is absolutely the consumption of some drug during the development of a sport test. It is also made a review to the causes by which they are drugged and characteristics that must put to us on the alert on a possible dopping, in addition to the conduct and advice to consider with the sportsmen in our consultations (AU)

Influence of analytical and biological variation on the clinical interpretation of seminal parameters.

Quality assurance in semen analysis has been questioned recently in this journal. Based on the limited capacity of seminal parameter in the determination of fertility, the authors advocated abandoning methods of quality assurance in semen analysis for clinical situations. In this article, we explore arguments as to why quality assurance in semen analysis for clinical use is not 'a waste of time'. Imprecision and within-subject biological variations are the two major components involved in the dispersion of seminal parameter results obtained by analysis of a semen sample from an individual. As within-subject biological variation is constant across geography, time and population, imprecision is a very important factor in the quality of laboratory test results. We analyse this influence on various seminal parameters and observe that there is an amount of error that can be tolerated without invalidating the medical usefulness of seminal parameter determination. However, there is a maximum allowable analytical error above which the medical usefulness of seminal parameter results is invalidated. The level of performance required to facilitate clinical decision-making is termed quality specification. We comment on different strategies to define the maximum allowable analytical error.

Quality specifications for seminal parameters based on the state of the art.

BACKGROUND: The aim of this study was to calculate the analytical goal for seminal parameters based on the state of the art, and then to compare these specifications with those previously obtained by our group based on biological variation. METHODS: All data used for analysis were derived from the Spanish programme of external quality control on semen analysis. Over 90 laboratories participated from 1999 to 2003. Using graphs of the state of the art, we also determined the numbers of laboratories that achieved quality specifications. RESULTS: The total allowable error calculated using state of the art graphs is similar to that calculated using biological variation for concentration and total motility. However, it is much higher for morphology and rapidly progressive motility. Over 80% of the laboratories achieved the minimum quality specification based on biological variation for concentration, total and progressive motility. However, only approximately 30% of the laboratories achieved the minimum quality specification based on biological variation for morphology and rapidly progressive motility. CONCLUSIONS: The study enabled us to identify the state of the art of analytical performance for seminal parameters, and revealed the difficulty inherent in meeting the quality specifications based on biological variation.

Estudio de calidad seminal en población joven del sudeste español / Study of semen quality in a young population from the southest of Spain

En los últimos 15 años han surgido varios trabajos en los que se advierte un posible descenso en la calidad seminal en el hombre. Estos estudios han sido criticados por el sesgo que pueden presentar en cuanto a la selección de las poblaciones de estudio y en cuanto a la metodología analítica empleada. En España, los trabajos realizados en este campo parten de poblaciones procedentes de bancos de donantes de semen y de clínicas de fertilidad. En el presente estudio partimos de una muestra de 271 jóvenes del sudeste de España, con edades entre 18 y 23 años, sin conocimiento previo sobre su salud reproductiva. Los jóvenes fueron reclutados para nuestro estudio durante un período continuo de 14 meses gracias a un plan de captación que fue llevado a cabo con la colaboración de la Universidad de Almería. A los jóvenes que accedieron a colaborar se les realizó un seminograma siguiendo la metodología de análisis estándar indicada por la OMS. Los valores de la media obtenidos para el volumen del eyaculado, concentración espermática y movilidad total fueron de 3,1 ml, 76 millones de espermatozoides/ml y 59,8 por ciento respectivamente, siendo estos valores similares a los encontrados en otros estudios europeos. Con estos datos se pretende crear una base de partida a la hora de hacer estudios comparativos. A su vez, establecemos un sistema de captación de voluntarios que puede ser de gran utilidad para futuros estudios en calidad seminal (AU)

Diagnóstico prenatal en una gestación gemelar con defecto del tubo neural en uno de los fetos / Prenatal diagnosis of a twin pregnancy with neural tube defect in one fetus

La alfafetoproteína y la acetilcolinesterasa son dos marcadores en líquido amniótico de defectos abiertos del tubo neural (DTN) fetal, pero por su conocida capacidad de difusión a través de la membrana amniótica, aunque no de esperar en la acetilcolinesterasa por su elevado peso molecular, en gestaciones gemelares en la que un feto presente DTN, la ecografía constituiría una técnica complementaria útil en la valoración del gemelo aparentemente normal, aunque sin la fiabilidad diagnóstica suficiente para descartar con seguridad la existencia de un DTN en este gemelo, como se describe en un caso de estas características acontecido en nuestro hospital (AU)