Paternal age is affected by genetic abnormalities, perinatal complications and mental health of the offspring

Genetics of female and male reproductive traits and their relationship with health, longevity and consequences for offspring

Substantial shifts in reproductive behaviors have recently taken place in many high-income countries including earlier age at menarche, advanced age at childbearing, rising childlessness and a lower number of children. As reproduction shifts to later ages, genetic factors may become increasingly important. Although monogenic genetic effects are known, the genetics underlying human reproductive traits are complex, with both causal effects and statistical bias often confounded by socioeconomic factors. Here, we review genome-wide association studies (GWASs) of 44 reproductive traits of both female and male individuals from 2007 to early 2024, examining reproductive behavior, reproductive lifespan and aging, infertility and hormonal concentration. Using the GWAS Catalog as a basis, from 159 relevant studies, we isolate 37 genes that harbor association signals for four or more reproductive traits, more than half of which are linked to rare Mendelian disorders, including ten genes linked to reproductive-related disorders: FSHB, MCM8, DNAH2, WNT4, ESR1, IGSF1, THRB, BRWD1, CYP19A1 and PTPRF. We also review the relationship of reproductive genetics to related health and behavioral traits, aging and longevity and the effect of parental age on offspring outcomes as well as reflecting on limitations, open questions and challenges in this fast-moving field.

Paternal aging impacts expression and epigenetic markers as early as the first embryonic tissue lineage differentiation

BACKGROUND

Advanced paternal age (APA) is associated with adverse outcomes to offspring health, including increased risk for neurodevelopmental disorders. The aim of this study was to investigate the methylome and transcriptome of the first two early embryonic tissue lineages, the inner cell mass (ICM) and the trophectoderm (TE), from human blastocysts in association with paternal age and disease risk. High quality human blastocysts were donated with patient consent from donor oocyte IVF cycles from either APA (≥ 50 years) or young fathers. Blastocysts were mechanically separated into ICM and TE lineage samples for both methylome and transcriptome analyses.

RESULTS

Significant differential methylation and transcription was observed concurrently in ICM and TE lineages of APA-derived blastocysts compared to those from young fathers. The methylome revealed significant enrichment for neuronal signaling pathways, as well as an association with neurodevelopmental disorders and imprinted genes, largely overlapping within both the ICM and TE lineages. Significant enrichment of neurodevelopmental signaling pathways was also observed for differentially expressed genes, but only in the ICM. In stark contrast, no significant signaling pathways or gene ontology terms were identified in the trophectoderm. Despite normal semen parameters in aged fathers, these significant molecular alterations can adversely contribute to downstream impacts on offspring health, in particular neurodevelopmental disorders like autism spectrum disorder and schizophrenia.

CONCLUSIONS

An increased risk for neurodevelopmental disorders is well described in children conceived by aged fathers. Using blastocysts derived from donor oocyte IVF cycles to strategically control for maternal age, our data reveals evidence of methylation dysregulation in both tissue lineages, as well as transcription dysregulation in neurodevelopmental signaling pathways associated with APA fathers. This data also reveals that embryos derived from APA fathers do not appear to be compromised for initial implantation potential with no significant pathway signaling disruption in trophectoderm transcription. Collectively, our work provides insights into the complex molecular mechanisms that occur upon paternal aging during the first lineage differentiation in the preimplantation embryo. Early expression and epigenetic markers of APA-derived preimplantation embryos highlight the susceptibility of the future fetus to adverse health outcomes.

Prospective prenatal cell-free DNA screening for genetic conditions of heterogenous etiologies

Prenatal cell-free DNA (cfDNA) screening uses extracellular fetal DNA circulating in the peripheral blood of pregnant women to detect prevalent fetal chromosomal anomalies. However, numerous severe conditions with underlying single-gene defects are not included in current prenatal cfDNA screening. In this prospective, multicenter and observational study, pregnant women at elevated risk for fetal genetic conditions were enrolled for a cfDNA screening test based on coordinative allele-aware target enrichment sequencing. This test encompasses the following three of the most frequent pathogenic genetic variations: aneuploidies, microdeletions and monogenic variants. The cfDNA screening results were compared to invasive prenatal or postnatal diagnostic test results for 1,090 qualified participants. The comprehensive cfDNA screening detected a genetic alteration in 135 pregnancies with 98.5% sensitivity and 99.3% specificity relative to standard diagnostics. Of 876 fetuses with suspected structural anomalies on ultrasound examination, comprehensive cfDNA screening identified 55 (56.1%) aneuploidies, 6 (6.1%) microdeletions and 37 (37.8%) single-gene pathogenic variants. The inclusion of targeted monogenic conditions alongside chromosomal aberrations led to a 60.7% increase (from 61 to 98) in the detection rate. Overall, these data provide preliminary evidence that a comprehensive cfDNA screening test can accurately identify fetal pathogenic variants at both the chromosome and single-gene levels in high-risk pregnancies through a noninvasive approach, which has the potential to improve prenatal evaluation of fetal risks for severe genetic conditions arising from heterogenous molecular etiologies. ClinicalTrials.gov registration: ChiCTR2100045739 .

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.

Impact of paternal age on assisted reproductive technology outcomes and offspring health: a systematic review

BACKGROUND

The increase in paternal age and the percentage of births after assisted reproductive technologies (ART) may have consequences on offspring and society's position regarding access to ART must be questioned. Most countries recommend limiting ART to men under 60 years. What is the rationale for this threshold?

OBJECTIVE

This systematic review assesses scientific arguments to establish links between paternal age, male fertility, and offspring health.

MATERIAL AND METHODS

Using the PRISMA guidelines, this systematic review of the literature analyzed 111 articles selected after screening PubMed, ScienceDirect, and Web of Science for articles published between January 1, 1995 and December 31, 2021.

RESULTS

A strong correlation was highlighted between advanced paternal age and a decrease of some sperm parameters (semen volume and sperm motility) and infant morbidity (exponentially increased incidence of achondroplasia and Apert syndrome, and more moderately increased incidence of autism and schizophrenia). The impact of paternal age on pregnancy and fetal aneuploidy rates is more controversial. No association was found with spontaneous abortion rates.

DISCUSSION AND CONCLUSION

The scientific parameters should be explained to older parents undergoing ART. And for countries that discuss a limit on paternal age for access to ART, the debate requires consideration of social and ethical arguments.

Incidence of cleft lip and palate, and epidemiology of perinatal deaths related to cleft lip and palate in Hunan Province, China, 2016-2020

This study aimed to analyze the epidemiological characteristics of cleft lip and/or palate (CL/P) and CL/P-related perinatal deaths, provide some information for intervention programs to reduce the incidence of CL/P and provide clues for future researchers. Data were obtained from the Birth Defects Surveillance System in Hunan Province, China, 2016-2020. Incidences of CL/P [number of cases per 1000 fetuses (births and deaths at 28 weeks of gestation and beyond)] with 95% confidence intervals (CI) were calculated by residence, gender, maternal age, year, and major types [cleft lip only (CL), cleft palate only (CP), and cleft lip with palate (CLP)]. Crude odds ratios (ORs) were calculated to examine the association of each maternal characteristic with CL/P. Pearson chi-square tests (χ²) were used to examine the association of each maternal characteristic with CL/P-related perinatal deaths. A total of 847,755 fetuses were registered, and 14,459 birth defects were identified, including 685 CL/P (accounted for 4.74% of all birth defects). CL, CP, and CLP accounted for 24.67% (169 cases), 36.79% (252 cases), and 38.54% (264 cases) of all CL/P, respectively. The incidence of CL/P was 0.81‰ (95%CI 0.75-0.87). The incidence of CL was 0.20‰ (95%CI 0.17-0.23) (169 cases), of CP was 0.30‰ (95%CI 0.26-0.33) (252 cases), and of CLP was 0.31‰ (95%CI 0.27-0.35) (264 cases). CL was more common in males than females (0.24‰ vs. 0.15‰, OR = 1.62, 95%CI 1.18-2.22). CP was more common in urban than rural (0.36‰ vs. 0.25‰, OR = 1.43, 95%CI 1.12-1.83), and less common in males than females (0.22‰ vs. 0.38‰, OR = 0.59, 95%CI 0.46-0.75). CLP was more common in males than females (0.35‰ vs. 0.26‰, OR = 1.36, 95%CI 1.06-1.74). Compared to mothers 25-29 years old, mothers < 20 years old were risk factors for CLP (OR = 3.62, 95%CI 2.07-6.33) and CL/P (OR = 1.80, 95%CI 1.13-2.86), and mothers ≥ 35 years old was a risk factor for CLP (OR = 1.43, 95%CI 1.01-2.02). CL/P-related perinatal deaths accounted for 24.96% (171/685) of all CL/P, of which 90.64% (155/171) were terminations of pregnancy. Rural residents, low income, low maternal age, and early prenatal diagnosis are risk factors for perinatal death. In conclusion, we found that CP was more common in urban areas and females, CL and CLP were more common in males, and CL/P was more common in mothers < 20 or ≥ 35 years old. In addition, most CL/P-related perinatal deaths were terminations of pregnancy. CL/P-related perinatal deaths were more common in rural areas, and the proportion of CL/P-related perinatal deaths decreased with the increase in maternal age, parity, and per-capita annual income. Several mechanisms have been proposed to explain these phenomena. Our study is the first systematic research on CL/P and CL/P-related perinatal deaths based on birth defects surveillance. It is significant for intervention programs to prevent CL/P and CL/P-related perinatal deaths. As well, more epidemiological characteristics of CL/P (such as the location of CL/P) and approaches to reduce CL/P-related perinatal deaths need to be studied in the future.

A new perspective on semen quality of aged male: The characteristics of metabolomics and proteomics

Background

Semen quality is negatively correlated with male age and is mainly quantified by a routine semen analysis, which is descriptive and inconclusive. Sperm proteins or semen metabolites are used as the intermediate or end-products, reflecting changes in semen quality, and hold much promise as a new biomarker to predict fertility in advanced-aged males.

Objectives

In this study, we sought to assess whether the semen metabolome and proteome of aged males can affect semen quality and serve as biomarkers for predicting semen quality.

Materials and methods

We retrospectively analyzed 12825 males that underwent semen routine analysis to understand the age-dependent changes in sperm quality. To identify the difference between aged and young adults, metabolomics (n=60) analyses of semen and proteomics (n=12) analyses of sperm were conducted. Finally, integrated machine learning of metabolomics was conducted to screen biomarkers to identify aging semen.

Results

We discovered that male age was positively correlated with sperm concentration as well as DNA fragmentation index(DFI), and negatively with progressive motile sperm count, total sperm count, sperm volume and progressive sperm motility. The differential metabolites were significantly enriched in various metabolic pathways, and four of these differential metabolites (Pipamperone, 2,2-Bis(hydroxymethyl)-2,2',2''-nitrilotriethanol, Arg-Pro and Triethyl phosphate) were utilized to establish a biomarker panel to identify aging semen. Proteomic analysis showed that differential proteins were significantly enriched in protein digestion and absorption and some energy-related pathways. An integrated analysis of the metabolome and proteome identified differential energy metabolism and oxidative stress-related proteins, which could explain the decreased motility and the increased DFI of aging sperm.

Discussion and conclusion

We provide compelling evidence that the changes in semen metabolome and sperm proteome are related to the decline of semen quality in aged males. Moreover, a biomarker panel based on four metabolites was established to identify aging semen.

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.

Diagnostic distribution and postnatal evaluation of prenatally detected short femur: A single center experience

Genetic skeletal disorders (GSDs) are clinically and etiologically heterogeneous group of disorders caused by abnormal growth and development of bone and/or cartilaginous tissues. Timely and accurate diagnosis is essential for prevention of significant comorbidities. In this study demographic, parental, prenatal and natal characteristics, and postnatal diagnostic distribution along with follow-up processes of 104 individuals with the finding of "short femur" detected in routine prenatal ultrasonography were evaluated. Of 104 patients, 19 (18.2%) were medically terminated, 12 (11.6%) were deceased during follow-up and 73 (70.2%) were still under follow-up. Diagnostic distribution of 104 patients was as follows: 77 (74%) had GSD, eight (7.7%) had chromosomal disorder, seven (6.7%) were completely normal, and 12 (11.5%) had no definite diagnosis. Long-term follow up evaluation contributed to clinical diagnosis in four patients. When grouped according to Nosology and Classification of GSDs: 2019 revision, the most frequent (n = 30, 38.5%) group was "FGFR3 chondrodysplasia group", followed by "Type 2 collagen group" (n = 7, 9%), and "Osteogenesis imperfecta and decreased bone density group" (n = 5, 6.4%). The finding of prenatally detected "short femur" represents a group of diverse diagnosis with heterogeneous etiology. GSDs are the most common etiology among fetuses with short extremity.

Association of assisted reproductive technology with autism spectrum disorder in the offspring: an updated systematic review and meta-analysis

This study aims to provide an up-to-date meta-analysis of data from studies investigating the risk of bearing a child with autism spectrum disorder (ASD) after being conceived by assisted reproductive technology (ART). The study was conducted according to the PRISMA Statement. PubMed and Scopus databases were searched up to August 2, 2020. Observational studies using a type of conception of assisted reproductive technology and examined as outcome offspring with ASD were included. A random effect model was applied due to the heterogeneity of the studies. Statistical analysis was performed with Stata 13 software. The Newcastle-Ottawa scale was used to assess the methodological quality of the included studies. The search strategy identified 587 potentially relevant studies. A total of 15 studies provided adequate data for statistical comparisons and, therefore, were included in the meta-analysis. Analysis of the subset of studies that examined all offspring and controlled for confounder factors revealed that the use of ART is associated with a higher risk of ASD (RR = 1.11, 95% CI = 1.03-1.19, p < 0.009), while in the case of studies that focused on singletons, a statistically significant association between ART and ASD was not observed (RR = 0.96, 95% CI = 0.82-1.13, p = 0.654).Conclusion: The present meta-analysis confirmed the existing positive correlation between ART and ASD in offspring, suggesting that ART is correlated with a higher risk for bearing a child with ASD. In contrast, this relationship is not confirmed in singletons. High quality prospective studies with a larger number of participants are still required. What is Known: • Studies that investigated the association between ART and ASD in offspring have shown conflicting results. • A previous meta-analysis showed that offspring conceived by ART are 1.35 times more likely to develop ASD than offspring spontaneously conceived. What is New: • This investigation separately considered studies with and without adjustment for confounders. • The findings from the two analyses were similar.

Have maternal or paternal ages any impact on the prenatal incidence of genomic copy number variants associated with fetal structural anomalies?

The objective of this study was to determine whether maternal or paternal ages have any impact on the prenatal incidence of genomic copy number variants (CNV) in fetuses with structural anomalies. We conducted a non-paired case-control study (1:2 ratio) among pregnancies undergoing chromosomal microarray analysis (CMA) because of fetal ultrasound anomalies, from December 2012 to May 2020. Pregnancies with any pathogenic copy number variant (CNV), either microdeletion or microduplication, were defined as cases. Controls were selected as the next two pregnancies with the same indication for CMA but with a normal result. Logistic regression was used, adjusting by use of assisted reproductive technology (ART) and parental smoking. Stratified analysis was performed according to CNV type (de novo/inherited and recurrent/non-recurrent). The study included 189 pregnancies: 63 cases and 126 controls. Mean maternal age in cases was 33.1 (SD 4.6) years and 33.9 (SD 6.0) years in controls. Mean paternal mean age was 34.5 (SD 4.8) years in cases and 35.8 (SD 5.8) years in controls. No significant differences in maternal or paternal age were observed, neither in stratified analysis according to the CNV type. Moreover, the proportion of cases were not significantly different between non-advanced and advanced ages, either considering paternal or maternal ages. The presence of pathogenic CNV at CMA in fetuses with structural anomalies was not found to be associated with advanced paternal or maternal age.

Advanced paternal age and risk of cancer in offspring

Many risk factors of cancer have been established, but the contribution of paternal age in this regard remains largely unexplored. To further understand the etiology of cancer, we investigated the relationship between paternal age and cancer incidence using PLCO cohort. Cox proportional hazards models were performed to assess the association between paternal age and the risk of cancers. During follow-up time (median 11.5 years), 18,753 primary cancers occurred. Paternal age was associated with reduced risk of cancers of the female genitalia (HR, 0.79; 95%CI, 0.66-0.94; P = 0.008) as well as cancers of the respiratory and intrathoracic organs (HR, 0.78; 95%CI, 0.63-0.97; P = 0.026). The association was stronger for lung cancer (HR, 0.67; 95%CI, 0.52-0.86; P = 0.002). The subgroup analysis suggested that age, gender, smoking and BMI were related to the decreased cancer incidence of the respiratory and intrathoracic organs, lung and the female genitalia. Positive linear associations were observed between paternal age and cancer incidence of the female genitalia, respiratory and intrathoracic organs and the lungs. These findings indicate that advanced paternal age is an independent protective factor against various cancers in offspring.