Effect of paternal age on human sperm chromosomes

Foal sex in Thoroughbred horses: related factors

Reproductive biotechniques in the equine species have advanced in the last decade and horse breeders have started to question the possibilities of interfering in the determination of foal sex. The aim of the present study was to verify whether the variables mares and stallion's age, side of the ovary containing the preovulatory follicle, preovulatory follicle diameter, time between breeding and ovulation, and ovulation inducing hormones influence the sex of the foal. A total of 259 reproductive cycles of 160 mares and 22 Thoroughbred stallions were used. Statistical analysis was performed using R software, including Pearson's chi-square test and logistic regression. Of the total foals born, 136 were males (52.51%) and 123 were females (47.49%). In mares that ovulated with -24h after ovulation induction, 104 foals (54.74%) were males and 86 (45.26%) were females, while in mares that ovulated with +24h, 32 foals (46.38%) were males and 37 (53.62%) were females. Stallions up to 15 years old had 44.14% (n=49) females and those over 15 years had 49.66% (n=73) females. The simple logistic regression model showed that mares and stallions under 15 years old, mares with ovulation time less than 24 hours and treated with Deslorelin had a higher probability of having male foals, but the Pearson's chi-square test showed that foals gender were not influenced by the variables studied.

Paternal age and risk for selected birth defects in a large South American sample

BACKGROUND

The relationship between maternal age (MA) and birth defects (BD) has been extensively studied while much less research, mostly with discordant results, has focused on the risk of paternal age (PA) for BD. Furthermore, no consensus has been reached on the best way to control the association of PA with MA.

OBJECTIVES

The aim of the study was to evaluate the risk of PA increase, at 1-year intervals, for selected BD, especially controlling for the confounding effect of MA.

METHODS

The sample comprised of 27,944 liveborns presenting 1 of 18 selected isolated BD. Conditional logistic regressions were applied to evaluate the risk of advanced PA and its yearly increase, adjusting by MA and other variables.

RESULTS

Of the 18 analyzed BD, only the risk for preaxial polydactyly (PreP) showed a significant association with increasing PA, while advanced MA was of low risk. For esophageal and anal atresia, associations with both PA and MA increases were observed.

CONCLUSIONS

Results support the hypothesis of advanced PA as a risk factor for PreP and helps clarify the so far unexplained nonrandom association between this defect and Down syndrome.

Genetic causes of sporadic and recurrent miscarriage

Approximately 80% of miscarriages happen within the first 12 weeks of gestation. More than half of early losses result from genetic defects, usually presenting as abnormal chromosome numbers or gene rearrangements in the embryo. However, the impact of genetics on pregnancy loss goes well beyond embryonic aneuploidy. For example, the use of big data has recently led to the discovery of specific gene mutations that may be implicated in sporadic and recurrent miscarriages. Further, emerging data suggest that genetic factors play a role in conditions for which there is a causative association with recurrent pregnancy loss. Here, we summarize the evidence on the genetics of miscarriage and provide an overview of the diagnosis and prevention of genetic causes associated with sporadic and recurrent pregnancy loss.

Advanced Paternal Age and Future Generations

Paternal age at conception has been increasing. In this review, we first present the results from the major mammalian animal models used to establish that increasing paternal age does affect progeny outcome. These models provide several major advantages including the possibility to assess multi- transgenerational effects of paternal age on progeny in a relatively short time window. We then present the clinical observations relating advanced paternal age to fertility and effects on offspring with respect to perinatal health, cancer risk, genetic diseases, and neurodevelopmental effects. An overview of the potential mechanism operating in altering germ cells in advanced age is presented. This is followed by an analysis of the current state of management of reproductive risks associated with advanced paternal age. The numerous challenges associated with developing effective, practical strategies to mitigate the impact of advanced paternal age are outlined along with an approach on how to move forward with this important clinical quandary.

New insights regarding origin of monosomy occurrence in early developing embryos as demonstrated in preimplantation genetic testing

Introduction

Analyses of miscarriage products indicate that the majority of aneuploidies in early developing embryos derive from errors occurring during maternal meiosis and the paternal contribution is less than 10%. Our aim was to assess the aneuploidy (mainly monosmies) frequencies at the earliest stages of embryo development, 3 days following fertilization during In vitro fertilization (IVF) treatments and to elucidate their parental origin. Later, we compared monosomies rates of day 3 to those of day 5 as demonstrated from Preimplantation Genetic Testing for Structural chromosomal Rearrangement (PGT-SR) results.

Methods

For a retrospective study, we collected data of 210 Preimplantation Genetic Testing for Monogenic Disorder (PGT-M) cycles performed between years 2008 and 2019.This study includes 2083 embryos, of 113 couples. It also included 432 embryos from 90 PGT-SR cycles of other 45 patients, carriers of balanced translocations. Defining the parental origin of aneuploidy in cleavage stage embryos was based on haplotypes analysis of at least six informative markers flanking the analyzed gene. For comprehensive chromosomal screening (CCS), chromosomal microarray (CMA) and next generation sequencing (NGS) was used.

Results

We inspected haplotype data of 40 genomic regions, flanking analyzed genes located on 9 different chromosomes.151 (7.2%) embryos presented numerical alterations in the tested chromosomes. We found similar paternal and maternal contribution to monosomy at cleavage stage. We demonstrated paternal origin in 51.5% of the monosomy, and maternal origin in 48.5% of the monosomies cases.

Conclusion

In our study, we found equal parental contribution to monosomies in cleavage-stage embryos. Comparison to CCS analyses of PGT-SR patients revealed a lower rate of monosomy per chromosome in embryos at day 5 of development. This is in contrast to the maternal dominancy described in studies of early miscarriage. Mitotic errors and paternal involvement in chemical pregnancies and IVF failure should be re-evaluated. Our results show monosomies are relatively common and may play a role in early development of ART embryos.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13039-022-00582-5.

Cytogenetic Analysis of the Products of Conception After Spontaneous Abortion in the First Trimester

In the present study, we retrospectively recruited 340 patients who underwent spontaneous abortions to investigate chromosomal abnormalities of the conception products in the first trimester. We also performed a relevant analysis of clinical factors. Of these patients, 165 had conception products with chromosomal abnormalities, including 135 aneuploidies, 11 triploidies, 10 complex abnormalities, and 9 segmental aneuploidies. The most common abnormal chromosomes were chromosome 16 in the embryo-transfer group and sex chromosomes in the natural-conception group. The most common abnormal chromosomes in all analyzed maternal age groups were sex chromosomes, 16, and 22. The chromosomal abnormality incidence was related to age and number of spontaneous abortions (both p < 0.05), but not to number of pregnancies, deliveries, induced abortions, or methods of conception (all p > 0.05). The rates of abnormality for chromosomes 12, 15, 20, and 22 increased with age, while the rates for chromosomes 6, 7, 13, and X decreased. In all age groups, aneuploidy was by far the most common abnormality; however, the low-incidence distributions of chromosomal abnormalities were entirely different. Overall, chromosomal aneuploidy was the primary cause of pregnancy loss in the first trimester, and low-frequency abnormalities differed across age subgroups. Chromosomal aberrations were found to be related to maternal age and spontaneous abortion, but not all chromosomal abnormalities increased with age.

Effect of male age on pregnancy and neonatal outcomes in the first frozen-thawed embryo transfer cycles of IVF/ICSI treatment

BACKGROUND

The effect of male age on pregnancy outcomes after assisted reproductive technology (ART) treatment shown in the previous literature is controversial. In addition, the influence of male age on neonatal outcomes following ART treatment has less been investigated.

OBJECTIVES

The aim of this study was to evaluate the effect of male age on reproductive and neonatal outcomes in couples following ART treatment.

MATERIALS AND METHODS

A retrospective cohort study was performed in two centers for assisted reproduction from June 2010 to February 2019. A total of 5512 frozen-thawed embryo transfer (FET) cycles were included according to the criteria. The primary outcome measures were pregnancy and neonatal outcomes. Patients were categorized into five groups according to male age (younger than 30, 31-35, 36-40, 41-45, and older than 45), and the group younger than 30 years old was treated as the reference group.

RESULTS

The logistic regression analysis showed that clinical pregnancy and live birth were all no statistic difference among the male age-groups compared with the reference group (p values, 0.743, 0.979, 0.948, 0.28; p values, 0.823, 0.342, 0.817, 0.381, respectively). Furthermore, no significant differences were found in the preterm birth rate, child sex, neonatal malformation, birth weight, and gestational age (p > 0.05). The advanced male age was not associated with a higher risk of adverse neonatal outcomes.

DISCUSSION AND CONCLUSION

This study showed that there were no effects of male age on pregnancy or neonatal outcomes in infertile couples following their first FET cycles when females were younger than 36 years old.

Sperm DNA methylation mediates the association of male age on reproductive outcomes among couples undergoing infertility treatment

Parental age at time of offspring conception is increasing in developed countries. Advanced male age is associated with decreased reproductive success and increased risk of adverse neurodevelopmental outcomes in offspring. Mechanisms for these male age effects remain unclear, but changes in sperm DNA methylation over time is one potential explanation. We assessed genome-wide methylation of sperm DNA from 47 semen samples collected from male participants of couples seeking infertility treatment. We report that higher male age was associated with lower likelihood of fertilization and live birth, and poor embryo development (p < 0.05). Furthermore, our multivariable linear models showed male age was associated with alterations in sperm methylation at 1698 CpGs and 1146 regions (q < 0.05), which were associated with > 750 genes enriched in embryonic development, behavior and neurodevelopment among others. High dimensional mediation analyses identified four genes (DEFB126, TPI1P3, PLCH2 and DLGAP2) with age-related sperm differential methylation that accounted for 64% (95% CI 0.42-0.86%; p < 0.05) of the effect of male age on lower fertilization rate. Our findings from this modest IVF population provide evidence for sperm methylation as a mechanism of age-induced poor reproductive outcomes and identifies possible candidate genes for mediating these effects.

Is there an association between paternal age and aneuploidy? Evidence from young donor oocyte-derived embryos: a systematic review and individual patient data meta-analysis

BACKGROUND

Delayed parenthood, by both women and men, has become more common in developed countries. The adverse effect of advanced maternal age on embryo aneuploidy and reproductive outcomes is well known. However, whether there is an association between paternal age (PA) and embryonic chromosomal aberrations remains controversial. Oocyte donation (OD) is often utilized to minimize maternal age effects on oocyte and embryo aneuploidy, thus providing an optimal model to assess the effect of PA. Several studies have revealed a higher than expected rate of aneuploidy in embryos derived from young oocyte donors, which warrants examination as to whether this may be attributed to advanced PA (APA).

OBJECTIVE AND RATIONALE

The objective of this systematic review and individual patient data (IPD) meta-analysis is to evaluate existing evidence regarding an association between PA and chromosomal aberrations in an OD model.

SEARCH METHODS

This review was conducted according to PRISMA guidelines for systematic reviews and meta-analyses. Medline, Embase and Cochrane databases were searched from inception through March 2020 using the (MeSH) terms: chromosome aberrations, preimplantation genetic screening and IVF. Original research articles, reporting on the types and/or frequency of chromosomal aberrations in embryos derived from donor oocytes, including data regarding PA, were included. Studies reporting results of IVF cycles using only autologous oocytes were excluded. Quality appraisal of included studies was conducted independently by two reviewers using a modified Newcastle-Ottawa Assessment Scale. A one-stage IPD meta-analysis was performed to evaluate whether an association exists between PA and aneuploidy. Meta-analysis was performed using a generalized linear mixed model to account for clustering of embryos within patients and clustering of patients within studies.

OUTCOMES

The search identified 13 032 references, independently screened by 2 reviewers, yielding 6 studies encompassing a total of 2637 IVF-OD cycles (n = 20 024 embryos). Two 'low' quality studies using FISH to screen 12 chromosomes on Day 3 embryos (n = 649) reported higher total aneuploidy rates and specifically higher rates of trisomy 21, 18 and 13 in men ≥50 years. One 'moderate' and three 'high' quality studies, which used 24-chromosome screening, found no association between PA and aneuploidy in Day 5/6 embryos (n = 12 559). The IPD meta-analysis, which included three 'high' quality studies (n = 10 830 Day 5/6 embryos), found no significant effect of PA on the rate of aneuploidy (odds ratio (OR) 0.97 per decade of age, 95% CI 0.91-1.03), which was robust to sensitivity analyses. There was no association between PA and individual chromosome aneuploidy or segmental aberrations, including for chromosomes X and Y (OR 1.06 per decade of age, 95% CI 0.92-1.21). Monosomy was most frequent for chromosome 16 (217/10802, 2.01%, 95% CI 1.76-2.29%) and trisomy was also most frequent for chromosome 16 (194/10802, 1.80%, 95% CI 1.56-2.06%).

WIDER IMPLICATIONS

We conclude, based on the available evidence, that APA is not associated with higher rates of aneuploidy in embryos derived from OD. These results will help fertility practitioners when providing preconception counselling, particularly to older men who desire to have a child.

Advanced paternal age: effects on sperm parameters, assisted reproduction outcomes and offspring health

Many factors, including postponement of marriage, increased life expectancy, and improved success with assisted reproductive technologies have been contributing to increased paternal age in developed nations. This increased average paternal age has led to concerns about adverse effects of advanced paternal age on sperm quality, assisted reproductive outcomes, and the health of the offspring conceived by older fathers. This review discusses the association between advanced paternal age and sperm parameters, assisted reproduction success rates, and offspring health.

Advanced paternal age and the risk of spontaneous abortion: an analysis of the combined 2011-2013 and 2013-2015 National Survey of Family Growth

BACKGROUND

Maternal and paternal age at first birth are increasing across the global population. Spontaneous abortion, one of the most common abnormal pregnancy outcomes, is known to occur more frequently with increasing maternal age. However, the relationship of advanced paternal age and spontaneous abortion is poorly understood, and previous results have yielded conflicting results.

OBJECTIVE

To examine the influence of paternal age on the risk of spontaneous abortion among singleton pregnancies conceived without assisted reproductive technologies.

MATERIALS AND METHODS

This was a retrospective, case-control study using combined pregnancy data from the Centers for Disease Control and Prevention's 2011-2013 and 2013-2015 National Survey of Family Growth. Spontaneous, singleton pregnancy data from women aged 15-45 years were analyzed. Ongoing pregnancies, induced abortions, ectopic pregnancies, preterm births, and intrauterine fetal deaths were excluded. Bivariate associations of pregnancy outcome (spontaneous abortion at <20 weeks and ≤12 weeks vs. live birth at ≥37 weeks) and paternal age were determined, along with those of maternal age and selected demographic and pregnancy characteristics. Significant associations were included in a multivariable logistic regression, which accounted for multiple pregnancies derived from the same respondent.

RESULTS

A total of 12,710 pregnancies from 6979 women were analyzed, consisting of 2300 (18.2%) spontaneous abortions and 10,410 (81.8%) term live births. Median maternal and paternal ages were 25 and 28 years, respectively. After adjusting for maternal age, race/ethnicity, socioeconomic status, marital status, and pregnancy intention, pregnancies resulting in spontaneous abortions had 2.05 (95% confidence interval, 1.06-2.20) times the odds of being from a father aged 50 years or older, vs. 25-29 years of age. These relationships remained significant when defining SABs at ≤12 weeks (adjusted odds ratio, 2.30; 95% confidence interval, 1.17-4.52).

CONCLUSION

Paternal age may increase the odds of spontaneous abortion, independent of selected factors, including demographics, pregnancy intention, and maternal age. This association was robust across several gestational age-based definitions of spontaneous abortion, even after adjustment.

Sexual conflict in action: An antagonistic relationship between maternal and paternal sex allocation in the tammar wallaby, Notamacropus eugenii

Sex ratio biases are often inconsistent, both among and within species and populations. While some of these inconsistencies may be due to experimental design, much of the variation remains inexplicable. Recent research suggests that an exclusive focus on mothers may account for some of the inconsistency, with an increasing number of studies showing variation in sperm sex ratios and seminal fluids. Using fluorescent in-situ hybridization, we show a significant population-level Y-chromosome bias in the spermatozoa of wild tammar wallabies, but with significant intraindividual variation between males. We also show a population-level birth sex ratio trend in the same direction toward male offspring, but a weaning sex ratio that is significantly female-biased, indicating that males are disproportionately lost during lactation. We hypothesize that sexual conflict between parents may cause mothers to adjust offspring sex ratios after birth, through abandonment of male pouch young and reactivation of diapaused embryos. Further research is required in a captive, controlled setting to understand what is driving and mechanistically controlling sperm sex ratio and offspring sex ratio biases and to understand the sexually antagonistic relationship between mothers and fathers over offspring sex. These results extend beyond sex allocation, as they question studies of population processes that assume equal input of sex chromosomes from fathers, and will also assist with future reproduction studies for management and conservation of marsupials.

Impact of advanced paternal age on the intracytoplasmic sperm injection (ICSI) outcomes in donor egg cycles

Background

The purpose of this study is to assess the impact of paternal age on the oocyte-donation outcomes in intracytoplasmic sperm injection (ICSI) cycles.

Methods

Two hundred and seventy-eight infertile couples were retrospectively involved. Inclusion criteria were: infertility from almost 1 year, normal or sub-fertile seminal parameters, overall oocyte survival rate greater than 85%. Baseline characteristics included male age, recipient age, male body mass index (BMI), smoking, drinking status. Main outcome measures: fertilization rate (FR), cleavage rate (CR), pregnancy rate (PR).

Results

Patients were categorized in group 1 ≤45, group 2 >45 years. A total of 1,724 frozen oocytes were included. After warming, 1,642 oocytes survived. Median overall oocyte survival rate was 100% [interquartile range (IQR), 85-100%]. Median male age was 44±5.60 years (IQR, 31-70 years). Median recipients age was 42±3.62 years (IQR, 29-50 years). Group 1 included 166 men, group 2 112 men. Two hundred and seventy-eight fresh ICSI cycle were performed. "Two-pronuclear" (2PN) FR was 72.6%±0.20%, CR 93.0%±0.16%, PR 39.6%. Miscarriage rate was 25.5%. Live birth rate per cycles was 29.5%. Comparison between group 1, group 2 and ICSI outcomes confirmed an association with FR, resulting 80.0% (IQR, 67.0-83.0%) and 67.0% (IQR, 50.0-80.0%), respectively (P<0.01). There were no significant differences between the two groups with respect to seminal parameters.

Conclusions

It would be recommended more emphasis on the advancing male age when counselling older couples who undergo egg donation program.

Impact of Paternal Age on Seminal Parameters and Reproductive Outcome of Intracytoplasmatic Sperm Injection in Infertile Italian Women

Background: We conducted a retrospective study on a cohort of couples attending the Department of Andrology and Reproductive Physiopathology at Sandro Pertini Hospital in Rome for Intracytoplasmatic Sperm Injection (ICSI)-assisted reproduction programs. Some of the couples included in the study underwent more than one ICSI cycle. Between January 2015 and April 2017. Objective: To evaluate whether the advancing of the paternal age may have effect on the seminal parameters, thus negatively affecting the embryo formation, development and quality, as well as the pregnancy rate. Materials and Methods: Five hundred and forty three ICSI cycles were performed on 439 couples undergoing Assisted Reproductive Technologies (ART). Patients were subdivided into three male and three female age groups having similar size: Men: ≤38 years (MI), 39-43 years (MII), ≥44 years (MIII). Women: ≤35 years (FI), 36-40 years (FII),≥41 years (FIII). Discussion and Conclusion: Male age groups did not reveal any statistical significant differences in any age-related semen parameters. We also confirmed a statistical significant increase in the pregnancy rate of couples with older partner age difference and younger female. We found that the advanced male age increases the probability of obtaining one or no type A embryo (NA≤1), which was almost doubled in the MIII group in comparison with MI, suggesting a negative effect of male age on the efficacy of the reproductive outcome in terms of a reduced number of type A embryos. Such an effect does not seem related to semen parameters and may deserve further investigations.

Comprehensive meta-analysis reveals association between multiple imprinting disorders and conception by assisted reproductive technology

PURPOSE

To determine whether a history of conception by assisted reproductive technology (ART) is associated with occurrence of one or more imprinting disorders of either maternal or paternal origin.

METHODS

We implemented a systematic review of scholarly literature followed by comprehensive meta-analysis to quantitatively synthesize data from reports relating to use of ART to occurrence of any imprinting disorder of humans, including Beckwith-Wiedemann (BWS), Angelman (AS), Prader-Willi (PWS), and Silver-Russell (SRS) syndromes, as well as transient neonatal diabetes mellitus (TNDB) and sporadic retinoblasoma (RB).

RESULTS

The systematic review identified 13 reports presenting unique data from 23 studies that related conception following ART to occurrence of imprinting disorders. Multiple studies of four disorder were identified, for which meta-analysis yielded the following summary estimates of associations with a history of ART: AS, summary odds ratio (sOR) = 4.7 (95% confidence interval (CI) 2.6-8.5, 4 studies); BWS, sOR = 5.8 (95% CI 3.1-11.1, 8 studies); PWS, sOR = 2.2 (95% CI 1.6-3.0, 6 studies); SRS, sOR = 11.3 (95% CI 4.5-28.5, 3 studies). Only one study reported on each of TNDB and RB.

CONCLUSION

Published data reveal positive associations between history of ART conception and each of four imprinting disorders. Reasons for these associations warrant further investigation.

Paternal age: Negative impact on sperm genome decays and IVF outcomes after 40 years

This study assessed sperm quality declining on relation to paternal age and its impact on in vitro fertilization (IVF) outcomes in order to estimate the APA (Advanced Paternal Age) cutoff. For this, 83 couples undergoing IVF treatment for male factor infertility were enrolled. The women age was ≤39 years, whereas the men were divided in two groups: APA (n = 41; age ≥ 40 years) and young (Y) (n = 42; age < 40 years). Conventional semen parameters (volume, concentration, motility, vitality, and morphology) were analyzed in the collected sperm samples. Furthermore, sperm genome decays (SGD) was assessed by TUNEL assay (DNA fragmentation), aniline blue staining (chromatin decondensation), and fluorescent in situ hybridization (aneuploidy). No significant difference was found concerning the conventional semen parameters between APA and Y groups. Conversely, SGD analysis showed increased DNA fragmentation; chromatin decondensation and sperm aneuploidy rates in the APA group (respectively, 41%, 43%, and 14% vs. 25%, 23%, and 4% in Y group). IVF outcomes also were affected by paternal age as indicated by the rates of cancelled embryo transfers, clinical pregnancy and miscarriage in the two groups APA and Y (29%, 17%, and 60% vs. 10%, 32%, and 42%). Finally, statistical analysis of the results suggests that the age of 40 should be considered as the APA cutoff during ART attempts.

The Effect of Paternal Age on Oocyte Donation Outcomes

IMPORTANCE

In recent decades, a trend toward delayed childbearing is noted in developed countries. Whereas the effects of maternal age on fertility, pregnancy complications, and postnatal outcomes have been thoroughly explored, consequences of advanced paternal age are less well known. Oocyte donation cycles can be used as an optimal model to analyze the association between male ageing and reproductive outcomes with minimal confounding.

OBJECTIVE

The purpose of this work was to summarize the updated and relevant literature dealing with the effect of paternal age on oocyte donation outcomes.

RESULTS

According to the available evidence from oocyte donation cycles, it seems that no significant association exists between advanced paternal age and fertility. However, this evidence is based on few studies, many of which are of low quality, yielding conflicting results. In addition, the emerging evidence clearly indicates an increased risk of adverse postnatal manifestations of pregnancies conceived by older fathers, including de novo autosomal dominant disorders, impaired neurocognitive development, and increased risk of malignancy.

CONCLUSIONS AND RELEVANCE

This review may be of aid to medical practitioners in counseling couples on the risks of delayed childbearing.

Paternal aging and increased risk of congenital disease, psychiatric disorders, and cancer

As couples are increasingly delaying parenthood, the effect of the aging men and women on reproductive outcomes has been an area of increased interest. Advanced paternal age has been shown to independently affect the entire spectrum of male fertility as assessed by reductions in sperm quality and fertilization (both assisted and unassisted). Moreover, epidemiological data suggest that paternal age can lead to higher rates of adverse birth outcomes and congenital anomalies. Mounting evidence also suggests increased risk of specific pediatric and adult disease states ranging from cancer to behavioral traits. While disease states associated with advancing paternal age have been well described, consensus recommendations for neonatal screening have not been as widely implemented as have been with advanced maternal age.

Effect of Paternal Age on Reproductive Outcomes of Intracytoplasmic Sperm Injection

The impact of paternal age on reproduction, especially using assisted reproductive technologies, has not been well studied to date. To investigate the effect of paternal age on reproductive outcomes, here we performed a retrospective analysis of 2,627 intracytoplasmic sperm injection (ICSI) cycles performed at the Reproductive Medicine Center of the Third Affiliated Hospital of Guangzhou Medical University (China) between January 2007 and May 2015. Effect of paternal age on embryo quality [number of fertilized oocytes, 2 pronucleus zygotes (2PNs), viable embryos, and high-quality embryos] was analyzed by multiple linear regression. Relationships between paternal age and pregnancy outcomes were analyzed by binary logistic regression. After adjusting for female age, no association between paternal age and the following parameters of embryo quality was observed: number of fertilized oocytes (B = -0.032; 95% CI -0.069–0.005; P = 0.088), number of 2PNs (B = -0.005; 95% CI -0.044–0.034; P = 0.806), and number of viable embryos (B = -0.025; 95% CI -0.052–0.001; P = 0.062). However, paternal age negatively influenced the number of high-quality embryos (B = -0.020; 95% CI -0.040–0.000; P = 0.045). Moreover, paternal age had no effect on pregnancy outcomes (OR for a 5-year interval), including the rates of clinical pregnancy (OR 0.919; 95% CI 0.839–1.006; P = 0.067), ongoing pregnancy (OR 0.914; 95% CI 0.833–1.003; P = 0.058), early pregnancy loss (OR 1.019; 95% CI 0.823–1.263; P = 0.861), live births (OR 0.916; 95% CI 0.833–1.007; P = 0.070), and preterm births (OR 1.061; 95% CI 0.898–1.254; P = 0.485). Therefore, increased paternal age negatively influences the number of high-quality embryos, but has no effect on pregnancy outcomes in couples undergoing ICSI cycles. However, more studies including men aged over 60 years with a longer-term follow-up are needed.

Sex ratio of equine offspring is affected by the ages of the mare and stallion

The aim of this study was to determine the influence of parental age on the sex ratio of offspring in horses. Two trials were performed. In the first trial, the data from a randomly obtained population with a 1:1 sex ratio of 59,950 Mangalarga Marchador horses born in Brazil from 1990 to 2011 were analyzed. The sex ratios of the offspring were compared among groups according to the mare and the stallion ages (from 3 to 25 years). In the first step of the analysis, the mares and stallions were grouped according to age in 5-year intervals. In the second step, the groups were based on the parental age gap at conception. In the third step, the group of the mares and stallions with similar ages from the second step was subdivided, and the different parental age subgroups that were divided into 5-year intervals were compared. In the fourth step, the sex ratio of the offspring was determined according to the ages of the mares and the stallions at conception. The second trial was based on the data from 253 horses of several breeds that were born after natural gestation into a herd from 1989 to 2010, and the offspring of groups that were younger or older than 15 years were compared. The data from both trials were analyzed using a chi-square test (P ≤ 0.01 for the first trial; and P ≤ 0.05 for the second trial) for the comparisons of the sex ratios. In the first trial, the Spearman test (P ≤ 0.01) was used to verify the correlations between the parental age and the offspring sex ratio. In the first trial, the offspring sex ratio decreased as the mare or stallion age increased, and the decrease was more marked for the mares than for the stallions. In the second trial, the mares older than 15 years had more fillies than the younger mares, but the stallion age had no effect on the sex of the offspring. The first trial, with a large number of horses, revealed the pattern of the distribution of the sex ratios of offspring according to the parental age in horses, whereas the second trial, with a more restricted number of horses, confirmed the influence of the age of the mare on the offspring sex ratio. We concluded that the parental age affected the offspring sex ratio in horses and that this effect was stronger for the mares than for the stallions.

Y fuse? Sex chromosome fusions in fishes and reptiles

Chromosomal fusion plays a recurring role in the evolution of adaptations and reproductive isolation among species, yet little is known of the evolutionary drivers of chromosomal fusions. Because sex chromosomes (X and Y in male heterogametic systems, Z and W in female heterogametic systems) differ in their selective, mutational, and demographic environments, those differences provide a unique opportunity to dissect the evolutionary forces that drive chromosomal fusions. We estimate the rate at which fusions between sex chromosomes and autosomes become established across the phylogenies of both fishes and squamate reptiles. Both the incidence among extant species and the establishment rate of Y-autosome fusions is much higher than for X-autosome, Z-autosome, or W-autosome fusions. Using population genetic models, we show that this pattern cannot be reconciled with many standard explanations for the spread of fusions. In particular, direct selection acting on fusions or sexually antagonistic selection cannot, on their own, account for the predominance of Y-autosome fusions. The most plausible explanation for the observed data seems to be (a) that fusions are slightly deleterious, and (b) that the mutation rate is male-biased or the reproductive sex ratio is female-biased. We identify other combinations of evolutionary forces that might in principle account for the data although they appear less likely. Our results shed light on the processes that drive structural changes throughout the genome.

Whether sperm deoxyribonucleic acid fragmentation has an effect on pregnancy and miscarriage after in vitro fertilization/intracytoplasmic sperm injection: a systematic review and meta-analysis

OBJECTIVE

To examine whether sperm DNA fragmentation has an effect on pregnancy and miscarriage after IVF and/or intracytoplasmic sperm injection (ICSI).

DESIGN

Systematic review and meta-analysis.

SETTING

University-affiliated teaching hospital.

PATIENT(S)

Infertility patient(s).

INTERVENTION(S)

An exhaustive electronic literature search was conducted on MEDLINE, Google Scholar, and the Cochrane Library, from database inception to October 2013. We included clinical trials that examined the influence of sperm DNA damage on pregnancy and miscarriage of IVF/ICSI.

MAIN OUTCOME MEASURE(S)

The outcomes of interest were pregnancy rate and miscarriage rate.

RESULT(S)

In the analysis of pregnancy, 16 cohort studies (3,106 couples) were included. Of these, 14 studies (2,756 couples, 965 pregnancies) that also mentioned miscarriage were identified in the analysis of miscarriage. Meta-analysis showed that high-level sperm DNA fragmentation has a detrimental effect on outcome of IVF/ICSI, with decreased pregnancy rate and increased miscarriage rate. The stratified analysis by type of procedure (IVF vs. ICSI) indicated that high sperm DNA damage was related to lower pregnancy rates in IVF but not in ICSI cycles, whereas it was associated with higher miscarriage rates in both IVF and ICSI cycles.

CONCLUSION(S)

The results indicate that assays detecting sperm DNA damage should be recommended to those suffering from recurrent failure to achieve pregnancy. Selection of sperm without DNA damage for use may improve the clinical outcome of ART. The data also provide a rationale for conducting further research aimed at evaluating the underlying mechanism(s) responsible for the detrimental effect of high sperm DNA fragmentation and the potential therapy.

The effect of sperm DNA fragmentation on miscarriage rates: a systematic review and meta-analysis

STUDY QUESTION

Is there an association between high levels of sperm DNA damage and miscarriage?

SUMMARY ANSWER

Miscarriage rates are positively correlated with sperm DNA damage levels.

WHAT IS KNOWN ALREADY

Most ejaculates contain a subpopulation of sperm with DNA damage, also referred to as DNA fragmentation, in the form of double or single-strand breaks which have been induced in the DNA prior to or following ejaculation. This DNA damage may be particularly elevated in some subfertile men, hence several studies have examined the link between sperm DNA damage levels and conception and miscarriage rates.

STUDY DESIGN, SIZE, DURATION

A systematic review and meta-analysis of studies which examined the effect of sperm DNA damage on miscarriage rates was performed. Searches were conducted on MEDLINE, EMBASE and the Cochrane Library without any language restrictions from database inception to January 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We used the terms 'DNA damage' or 'DNA fragmentation' combined with 'miscarriage', 'abortion' or 'pregnancy' to generate a set of relevant citations. Data extraction was performed by two reviewers. Study quality was assessed using the Newcastle-Ottawa Scale. Meta-analysis of relative risks of miscarriage was performed with a random effects model. Subgroup analyses were performed by the type of DNA damage test, whether the sperm examined were prepared or from raw semen and for pregnancies resulting from IVF or ICSI treatment.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified 16 cohort studies (2969 couples), 14 of which were prospective. Eight studies used acridine orange-based assays, six the TUNEL assay and two the COMET assay. Meta-analysis showed a significant increase in miscarriage in patients with high DNA damage compared with those with low DNA damage [risk ratio (RR) = 2.16 (1.54, 3.03), P < 0.00001)]. A subgroup analysis showed that the miscarriage association is strongest for the TUNEL assay (RR = 3.94 (2.45, 6.32), P < 0.00001).

LIMITATIONS, REASONS FOR CAUTION

There is some variation in study characteristics, including the use of different assays and different thresholds for DNA damage and the definition of pregnancy loss.

WIDER IMPLICATIONS OF THE FINDINGS

The use of methods which select sperm without DNA damage for use in assisted conception treatment may reduce the risk of miscarriage. This finding indicates that assays detecting DNA damage could be considered in those suffering from recurrent pregnancy loss. Further research is necessary to study the mechanisms of DNA damage and the potential therapeutic effects of antioxidant therapy.

STUDY FUNDING/COMPETING INTEREST(S)

None.

Advanced paternal age and reproductive outcome

Women have been increasingly delaying the start of motherhood in recent decades. The same trend is seen also for men. The influence of maternal age on fertility, chromosomal anomalies, pregnancy complications, and impaired perinatal and post-natal outcome of offspring, has been thoroughly investigated, and these aspects are clinically applied during fertility and pregestational counseling. Male aging and reproductive outcome has gained relatively less attention. The purpose of this review is to evaluate updated and relevant literature on the effect of paternal age on reproductive outcome.

Determination of the correlation between stallion's age and number of sex chromosome aberrations in spermatozoa

The aim of this study was a cytogenetic analysis of stallions semen to find sex chromosome aberrations and to determine if there was an association between stallion's age and aberration frequency for the sex chromosomes. Sperm samples were collected from 22 stallions of various age from 3 to 23 years. Multicolour FISH was performed on each sample, using probes for the sex chromosomes and EGFR gene, localized on 4p12 in domestic horse. A total of 26199 sperm cells were analysed (from 1 070 to 1 532 per animal). Among the analysed cells, there were 50.318% with X chromosome, 48.543% with Y chromosome and 1.139% with aberrant chromosomes. The frequency of aberrations was: sex chromosomes nullisomy (0.466%), XY aneuploidy (0.454%), XX disomy (0.146%), YY disomy (0.041%), diploidy (0.024%) and trisomy XXY (0.008%). Additionally there was a correlation between the age of an animal and the frequency of sex chromosome aberration and a significant positive correlation between age and disomy of XY, XX, YY, trisomy of XXY, autosomal disomy was seen. A Correlation between the age of a stallion and the level of nullisomy was negative. The present study demonstrated that FISH technique is a powerful method to identify sex chromosome aberrations in equine spermatozoa and might be very helpful for a breeder during a selection for the best stallion.

Advanced age increases chromosome structural abnormalities in human spermatozoa

This study explores the relationship between sperm structural aberrations and age by using a multicolor multichromosome FISH strategy that provides information on the incidence of duplications and deletions on all the autosomes. ToTelvysion kit (Abbott Molecular, Abbott Park, IL, USA) with telomere-specific probes was used. We investigated the sperm of 10 male donors aged from 23 to 74 years old. The donors were divided into two groups according to age, a cohort of five individuals younger than 40 and a cohort of five individuals older than 60 years. The goal of this study was to determine (1) the relationship between donor age and frequency and type of chromosome structural abnormalities and (2) chromosomes more frequently involved in sperm structural aberrations. We found that the older patients had a higher rate of structural abnormalities (6.6%) compared with the younger cohort (4.9%). Although both duplications and deletions were seen more frequently in older men, our findings demonstrate the presence of an excess of duplications versus deletions in both groups at a ratio of 2 to 1. We demonstrate that the distribution of duplications and deletions was not linear along the chromosomes, although a trend toward a higher rate of abnormalities in larger chromosomes was observed. This work is the first study addressing the frequencies of sperm chromosome structural aberrations of all autosomes in a single assay thus making a contribution to the clarification of the amount and origin of damage present in human spermatozoa and in relation to age.

The effect of age on the expression of apoptosis biomarkers in human spermatozoa

OBJECTIVE

To evaluate the impact of age on the expression of apoptotic biomarkers in human spermatozoa.

DESIGN

Cross sectional, prospective study.

SETTING

Academic centers.

PATIENT(S)

Healthy volunteers with proven fertility, stratified by age (n = 25, range: 20-68 years).

INTERVENTION(S)

Examination of serum hormone levels and basic semen parameters, and assessment of early (plasma membrane translocation of phosphatidylserine) and late (DNA fragmentation) sperm apoptotic markers by flow cytometry (using Annexin-V binding and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling).

MAIN OUTCOME MEASURE(S)

Apoptosis markers.

RESULT(S)

Advancing male age was significantly and positively correlated with Annexin-V binding results. Although not significant, there was a clear trend for increased DNA fragmentation in the older groups. The age threshold for these observations appears to be 40 years. Advancing male age was positively correlated with FSH and sex hormone-binding globulin (SHBG) levels, and negatively correlated with sperm concentration.

CONCLUSION(S)

Advancing male age is associated with the expression of early apoptotic markers as evidenced by significantly increased plasma membrane translocation of phosphatidylserine, as well as with a more subtle proportion of sperm carrying DNA fragmentation. This study confirmed that male age is also associated with a decline in sperm concentration.

Association of paternal age and risk for major congenital anomalies from the National Birth Defects Prevention Study, 1997 to 2004

PURPOSE

The objective of this study was to examine the associations between paternal age and birth defects of unknown etiologies while carefully controlling for maternal age.

METHODS

By using 1997 to 2004 data from the National Birth Defects Prevention Study, we fit logistic regression models with paternal and maternal age as continuous variables while adjusting for demographic and other factors.

RESULTS

Elevated odds ratios (ORs) for each year increase in paternal age were found for cleft palate (OR. 1.02, 95% confidence interval [95% CI], 1.00-1.04), diaphragmatic hernia (OR, 1.04; 95% CI, 1.02-1.06), right ventricular outflow tract obstruction (OR, 1.03; 95% CI, 1.01-1.04), and pulmonary valve stenosis (OR, 1.02, 95% CI, 1.01-1.04). At younger paternal ages, each year increase in paternal age correlated with increased odds of having offspring with encephalocele, cataract, esophageal atresia, anomalous pulmonary venous return, and coarctation of the aorta, but these increased odds were not observed at older paternal ages. The effect of paternal age was modified by maternal age for gastroschisis, omphalocele, spina bifida, all orofacial clefts, and septal heart defects.

CONCLUSIONS

Our findings suggest that paternal age may be a risk factor for some multifactorial birth defects.

Predictive factors of repeat sperm aspiration success

OBJECTIVES

To evaluate the outcomes of repeated testicular sperm aspirations (TESAs) and to investigate whether the interval between TESA procedures, success in the first attempt, and patient age might influence the results.

METHODS

The patient population in the present study consisted of couples undergoing TESA for intracytoplasmic sperm injection. Of these, 189, 46, 42, and 19 male patients underwent 1, 2, 3, and 4 sperm retrievals, respectively. The effects of the interval between TESA procedures, success of the previous attempts, and patient age on sperm recuperation in a repeated procedure were evaluated.

RESULTS

Of the patients with nonobstructive azoospermia from whom sperm was not retrieved in the first procedure, 16.6% had successful sperm retrieval at the second procedure. In 57.1% of the patients who did not achieve sperm recuperation for the second attempt, sperm could be retrieved in the third procedure. Finally, of the patients without success in the third attempt, 40.0% had successful sperm retrieval at the fourth attempt. Success in the preceding TESA procedure positively influenced the success of sperm retrieval in a repeated attempt, and a trend for a negative effect of paternal age in the success of a repeated TESA attempt was noted. However, the interval between procedures had no influence on TESA success.

CONCLUSIONS

The results of our study have shown that patient age and the success of the first TESA may predict the results of additional attempts. However, TESA may result in sperm recovery even when the first recovery procedure was not successful. Moreover, sperm recovery did not seem to be affected by the interval between procedures.

Negative influence of paternal age on clinical intracytoplasmic sperm injection cycle outcomes in oligozoospermic patients

OBJECTIVE

To evaluate the effect of male age on clinical outcomes of intracytoplasmic sperm injection (ICSI) cycles, according to sperm concentration.

DESIGN

Retrospective, observational study.

SETTING

Assisted reproduction center.

PATIENT(S)

The study included 1,024 couples undergoing ICSI cycles with fresh spermatozoa.

INTERVENTION(S)

The influence of paternal age on ICSI outcomes of oligozoospermic and normozoospermic patients was evaluated.

MAIN OUTCOME MEASURE(S)

Rates of high-quality embryos, pregnancy, implantation, and miscarriage were evaluated through linear logistic regression analyses.

RESULT(S)

When the sperm concentration was abnormal, paternal age influenced implantation (regression coefficient value = -0.7009) and pregnancy rates (odds ratio = 0.95, 95% confidence interval 0.91-0.99). However, in normozoospermic patients, no influence of paternal age was observed on implantation (regression coefficient value = 0.0566) or pregnancy rates (odds ratio = 1.00, 95% confidence interval 0.97-1.03).

CONCLUSION(S)

For couples in which the men are oligozoospermic, the implantation rate could be impaired by increased paternal age. In these couples, the chance of pregnancy decreased 5% for each year of paternal age. When men are normozoospermic, this effect is not observed.

The role of rare structural variants in the genetics of autism spectrum disorders

Autism is a neurodevelopmental disorder characterized by impaired social interaction and communication and restricted interests and behaviors. Despite high estimates of heritability, genetic causes of ASD have long been elusive, due in part to a high degree of genetic and phenotypic heterogeneity (Bailey et al., 1995). Recently, important advances have been made in the genetics of ASD with the use of new technologies for the direct detection of copy number variation (CNV) in the human genome. CNV studies have revealed that de novo deletions and duplications, typically less than 1 Mb in size, are strongly associated with ASD, suggesting that spontaneous structural mutations play a more important role in the etiology of disease than was previously recognized. Rare mutations have been identified at many different locations in the genome, and multiple 'hot spots' have been identified where identical rearrangements recur with high frequency. These findings are consistent with the hypothesis that autism, like mental retardation, is caused by a large number of individually rare mutations. These studies serve as a model for how other emerging technologies for mutation detection (e.g. next generation sequencing platforms) could be used to further elucidate the role of rare sequence changes in ASD.

Influence of paternal age on assisted reproduction outcome

There has been an increasing tendency to delay parenthood in developed countries in recent years, and there is not enough information available regarding the effect of this on fertility. The aim of this work was to determine the role of paternal age on the outcome of assisted reproduction. A retrospective study was designed comprising a total of 2204 intrauterine insemination (IUI) cycles, 1286 IVF cycles and 1412 IVF cycles with donated oocytes during the period 2000 to 2006. Male mean age was 34.3 years (range 25-56) for IUI, 34.8 years (range 19-62) for IVF and 41.10 years (range 25-71) for ovum donation cycles. Statistics revealed no differences regarding pregnancy and miscarriage rates when the results were compared among age groups. In standard IVF and ovum donation cycles there was no clear association between embryo quality and paternal age. There was no significant relationship between male age and implantation rate. So far this is the largest study concerning the relevance of male age in assisted reproduction. As confirmed by the present data, the effect of the age of the male in the range studied is irrelevant. This finding contributes to the information that can be provided to infertile couples.

Statement on guidance for genetic counseling in advanced paternal age

In 1996, a practice guideline on genetic counseling for advanced paternal age was published. The current document updates the state of knowledge of advanced paternal age effects on single gene mutations, chromosome anomalies, and complex traits.

Paternal effects on early embryogenesis

Historically, less attention has been paid to paternal effects on early embryogenesis than maternal effects. However, it is now apparent that certain male factor infertility phenotypes are associated with increased DNA fragmentation and/or chromosome aneuploidies that may compromise early embryonic development. In addition, there is a growing body of evidence that the fertilizing sperm has more function than just carrying an intact, haploid genome. The paternally inherited centrosome is essential for normal fertilization, and the success of higher order chromatin packaging may impact embryogenesis. Epigenetic modifications of sperm chromatin may contribute to the reprogramming of the genome, and sperm delivered mRNA has also been hythesized to be necessary for embryogenesis. There is less information about the epigenetic factors affecting embryogenesis than genetic factors, but the epigenetics of gamete and early embryogenesis is a rapidly advancing field.

Frequency of human sperm carrying structural aberrations of chromosome 1 increases with advancing age

OBJECTIVE

To investigate the association between male age and the frequency of sperm with de novo structural chromosomal abnormalities.

DESIGN

Semen specimens collected from two groups of 10 healthy, nonsmoking men, aged 22-28 and 65-80 years, were analyzed with the use of a multicolor fluorescence in situ hybridization assay for detecting breaks, segmental duplications and deletions, and aneuploidy and diploidy involving chromosome 1.

SETTING

Healthy volunteer workers and retirees from a government research environment.

MAIN OUTCOME MEASURE

Sperm carrying numerical and structural chromosomal abnormalities.

RESULT(S)

We detected significant increases in the frequency of sperm carrying breaks and segmental duplications and deletions of chromosome 1 among older men compared with younger men. Older men carried twice the frequency of sperm with segmental duplications and deletions of chromosome 1. The frequency of sperm carrying breaks within the 1q12 fragile-site region nearly doubled in older men. In contrast to female gametes, there was no effect of age on the frequency of sperm with numerical chromosomal abnormalities.

CONCLUSION

Our findings suggest that advancing male age is associated with a gradual and significant increase in the risk of fathering children with various chromosomal defects such as segmental aneusomy syndromes.