Reproductive outcomes in individuals with chromosomal reciprocal translocations.

PURPOSE: Patients with reciprocal balanced translocations (RBT) have a risk for recurrent pregnancy losses (RPL), affected child, and infertility. Currently, genetic counseling is based on karyotypes found among the products of conception (POC), although factors influencing the success of assisted reproductive technologies (ART) in RBT couples are not established. METHODS: Cytogenetic results from 261 POC and offspring of the parents (113 women and 90 men) with RBT were evaluated. Chromosome segregation modes and number of euploid embryos were assessed in couples undergoing in vitro fertilization. RESULTS: Patients with translocations involving an acrocentric chromosome have a higher risk of unbalanced gametes caused by a 3:1 segregation. Female RBT patients have a statistically higher risk of aneuploidy due to an interchromosomal effect. The rate of euploid embryos is low due to meiosis I malsegregation of RBT, meiosis II nondisjunction, additional whole chromosome or segmental aneusomies. RBT patients with RPL have a higher rate of miscarriage of euploid fetuses with RBT. CONCLUSION: Chromosome-specific factors, female gender, age, and history of RPL are the risk elements influencing pregnancy and in vitro fertilization success in RBT patients. Chromosomal microarray analysis of POC is necessary to provide an accurate and timely diagnosis for patients with adverse reproductive outcomes.

Chromosomal instability in women with primary ovarian insufficiency.

STUDY QUESTION: What is the prevalence of somatic chromosomal instability among women with idiopathic primary ovarian insufficiency (POI)? SUMMARY ANSWER: A subset of women with idiopathic POI may have functional impairment in DNA repair leading to chromosomal instability in their soma. WHAT IS KNOWN ALREADY: The formation and repair of DNA double-strand breaks during meiotic recombination are fundamental processes of gametogenesis. Oocytes with compromised DNA integrity are susceptible to apoptosis which could trigger premature ovarian aging and accelerated wastage of the human follicle reserve. Genomewide association studies, as well as whole exome sequencing, have implicated multiple genes involved in DNA damage repair. However, the prevalence of defective DNA damage repair in the soma of women with POI is unknown. STUDY DESIGN, SIZE, DURATION: In total, 46 women with POI and 15 family members were evaluated for excessive mitomycin-C (MMC)-induced chromosome breakage. Healthy fertile females (n = 20) and two lymphoblastoid cell lines served as negative and as positive controls, respectively. PARTICIPANTS/MATERIALS, SETTING, METHODS: We performed a pilot functional study utilizing MMC to assess chromosomal instability in the peripheral blood of participants. A high-resolution array comparative genomic hybridization (aCGH) was performed on 16 POI patients to identify copy number variations (CNVs) for a set of 341 targeted genes implicated in DNA repair. MAIN RESULTS AND THE ROLE OF CHANCE: Array CGH revealed three POI patients (3/16, 18.8%) with pathogenic CNVs. Excessive chromosomal breakage suggestive of a constitutional deficiency in DNA repair was detected in one POI patient with the 16p12.3 duplication. In two patients with negative chromosome breakage analysis, aCGH detected a Xq28 deletion comprising the Centrin EF-hand Protein 2 (CETN2) and HAUS Augmin Like Complex Subunit 7 (HAUS7) genes essential for meiotic DNA repair, and a duplication in the 3p22.2 region comprising a part of the ATPase domain of the MutL Homolog 1 (MLH1) gene. LIMITATIONS REASONS FOR CAUTION: Peripheral lymphocytes, used as a surrogate tissue to quantify induced chromosome damage, may not be representative of all the affected tissues. Another limitation pertains to the MMC assay which detects homologous repair pathway defects and does not test deficiencies in other DNA repair pathways. WIDER IMPLICATIONS OF THE FINDINGS: Our results provide evidence for functional impairment of DNA repair in idiopathic POI, which may predispose the patients to other DNA repair-related conditions such as accelerated aging and/or cancer susceptibility. STUDY FUNDING/COMPETING INTEREST(S): Funding was provided by the National Institute of Child Health and Human Development. There were no competing interests to declare.

Inter- and intra-individual variation in allele-specific DNA methylation and gene expression in children conceived using assisted reproductive technology.

Epidemiological studies have reported a higher incidence of rare disorders involving imprinted genes among children conceived using assisted reproductive technology (ART), suggesting that ART procedures may be disruptive to imprinted gene methylation patterns. We examined intra- and inter-individual variation in DNA methylation at the differentially methylated regions (DMRs) of the IGF2/H19 and IGF2R loci in a population of children conceived in vitro or in vivo. We found substantial variation in allele-specific methylation at both loci in both groups. Aberrant methylation of the maternal IGF2/H19 DMR was more common in the in vitro group, and the overall variance was also significantly greater in the in vitro group. We estimated the number of trophoblast stem cells in each group based on approximation of the variance of the binomial distribution of IGF2/H19 methylation ratios, as well as the distribution of X chromosome inactivation scores in placenta. Both of these independent measures indicated that placentas of the in vitro group were derived from fewer stem cells than the in vivo conceived group. Both IGF2 and H19 mRNAs were significantly lower in placenta from the in vitro group. Although average birth weight was lower in the in vitro group, we found no correlation between birth weight and IGF2 or IGF2R transcript levels or the ratio of IGF2/IGF2R transcript levels. Our results show that in vitro conception is associated with aberrant methylation patterns at the IGF2/H19 locus. However, very little of the inter- or intra-individual variation in H19 or IGF2 mRNA levels can be explained by differences in maternal DMR DNA methylation, in contrast to the expectations of current transcriptional imprinting models. Extraembryonic tissues of embryos cultured in vitro appear to be derived from fewer trophoblast stem cells. It is possible that this developmental difference has an effect on placental and fetal growth.

DNA methylation and gene expression differences in children conceived in vitro or in vivo.

Epidemiological data indicate that children conceived in vitro have a greater relative risk of low birth-weight, major and minor birth defects, and rare disorders involving imprinted genes, suggesting that epigenetic changes may be associated with assisted reproduction. We examined DNA methylation at more than 700 genes (1536 CpG sites) in placenta and cord blood and measured gene expression levels of a subset of genes that differed in methylation levels between children conceived in vitro versus in vivo. Our results suggest that in vitro conception is associated with lower mean methylation at CpG sites in placenta and higher mean methylation at CpG sites in cord blood. We also find that in vitro conception-associated DNA methylation differences are associated with gene expression differences at both imprinted and non-imprinted genes. The range of inter-individual variation in gene expression of the in vitro and in vivo groups overlaps substantially but some individuals from the in vitro group differ from the in vivo group mean by more than two standard deviations. Several of the genes whose expression differs between the two groups have been implicated in chronic metabolic disorders, such as obesity and type II diabetes. These findings suggest that there may be epigenetic differences in the gametes or early embryos derived from couples undergoing treatment for infertility. Alternatively, assisted reproduction technology may have an effect on global patterns of DNA methylation and gene expression. In either case, these differences or changes may affect long-term patterns of gene expression.

Obstetric outcomes with a false-positive one-hour glucose challenge test by the Carpenter-Coustan criteria.

OBJECTIVE: Pregnancies complicated by a false-positive one-hour glucose challenge test (GCT), as determined by the National Diabetes Data Group (NDDG) criteria, have higher rates of adverse maternal and neonatal outcomes. This study was conducted to determine if pregnancies complicated by a false-positive GCT, as determined by the Carpenter-Coustan (CC) criteria, also have higher rates of adverse maternal and neonatal outcomes. STUDY DESIGN: In this retrospective case-control study, we compared 165 patients with a false-positive GCT, as determined by the Carpenter-Coustan criteria, to a cohort of 165 pregnant controls with a normal screening GCT. Multiple variables for maternal and neonatal outcomes were compared between the two groups. RESULTS: The racial distribution and gestational age of delivery were similar in both groups. The study group had a higher one-hour GCT (148.2 mg/dl vs. 95.3 mg/dl, p < 0.001), was older (27.4 yrs vs. 23.8 years, p < 0.001), was more likely to be multiparous (71.5% vs. 58.2%, p = 0.011), and had a higher BMI (26.7 kg/m2 vs. 24.6 kg/m2, p = 0.002). There were no differences between the two groups in mode of delivery, birth weight, rates of macrosomia, shoulder dystocia, antenatal death and maternal laceration. There were also no differences between the two groups in rates of preeclampsia, chorioamnionitis, endometritis, ICN admission, neonatal hypoglycemia, Erb's palsy, clavicular fracture, neonatal sepsis, neonatal death or use of phototherapy. CONCLUSION: Women with a false-positive one-hour GCT by the Carpenter-Coustan criteria do not have higher rates of adverse perinatal outcomes. Using the Carpenter-Coustan criteria to diagnose GDM appears to be superior to NDDG criteria in terms of avoiding adverse maternal and neonatal outcomes.

Functional study of a novel missense single-nucleotide variant of NUP107 in two daughters of Mexican origin with premature ovarian insufficiency.

BACKGROUND: Hypergonadotropic hypogonadism (HH) is a genetically heterogeneous disorder that usually presents with amenorrhea, atrophic ovaries, and low estrogen. Most cases of HH are idiopathic and nonsyndromic. Nucleoporin 107 (NUP107), a protein involved in transport between cytoplasm and nucleus with putative roles in meiosis/mitosis progression, was recently implicated as a cause of HH. We identified a NUP107 genetic variant in a nonconsanguineous family with two sisters affected with primary amenorrhea and HH, and generated a mouse model that carried the human variant. METHODS: We performed a high-resolution X-chromosome microarray and whole exome sequencing on parents and two sisters with HH to identify pathogenic variants. We generated a mouse model of candidate NUP107 variant using CRISPR/Cas9. RESULTS: Whole exome sequencing identified a novel and rare missense variant in the NUP107 gene (c.1063C>T, p.R355C) in both sisters with HH. In order to determine functional significance of this variant, we used CRISPR/Cas9 to introduce the human variant into the mouse genome. Mice with the homolog of the R355C variant, as well as the nine base pairs deletion in Nup107 had female subfertility. CONCLUSIONS: Our findings indicate that NUP107 R355C variant falls in the category of variant of unknown significance as the cause of HH and infertility.

Baking soda pica: a case of hypokalemic metabolic alkalosis and rhabdomyolysis in pregnancy.

BACKGROUND: We report a case of baking soda pica in a woman at 31 weeks of pregnancy causing severe hypokalemic metabolic alkalosis and rhabdomyolysis. CASE: A multigravida at 31 weeks of gestation presented with weakness and muscle pain. She was found to have severe hypokalemic metabolic alkalosis and rhabdomyolysis, with elevation in serum transaminases and hypertension. We initially thought the patient had an atypical presentation of preeclampsia until it was realized that she was ingesting 1 full box of baking soda (454 g sodium bicarbonate) per day. Symptoms and abnormal laboratory findings resolved with discontinuation of the patient's pica practices. CONCLUSION: Pica is a common but often overlooked practice that can potentially lead to life-threatening disorders. A thorough evaluation of a patient's dietary intake is extremely important, especially in the setting of atypical presentations of disease in pregnancy.

DNA methylation differences at growth related genes correlate with birth weight: a molecular signature linked to developmental origins of adult disease?

BACKGROUND: Infant birth weight is a complex quantitative trait associated with both neonatal and long-term health outcomes. Numerous studies have been published in which candidate genes (IGF1, IGF2, IGF2R, IGF binding proteins, PHLDA2 and PLAGL1) have been associated with birth weight, but these studies are difficult to reproduce in man and large cohort studies are needed due to the large inter individual variance in transcription levels. Also, very little of the trait variance is explained. We decided to identify additional candidates without regard for what is known about the genes. We hypothesize that DNA methylation differences between individuals can serve as markers of gene "expression potential" at growth related genes throughout development and that these differences may correlate with birth weight better than single time point measures of gene expression. METHODS: We performed DNA methylation and transcript profiling on cord blood and placenta from newborns. We then used novel computational approaches to identify genes correlated with birth weight. RESULTS: We identified 23 genes whose methylation levels explain 70-87% of the variance in birth weight. Six of these (ANGPT4, APOE, CDK2, GRB10, OSBPL5 and REG1B) are associated with growth phenotypes in human or mouse models. Gene expression profiling explained a much smaller fraction of variance in birth weight than did DNA methylation. We further show that two genes, the transcriptional repressor MSX1 and the growth factor receptor adaptor protein GRB10, are correlated with transcriptional control of at least seven genes reported to be involved in fetal or placental growth, suggesting that we have identified important networks in growth control. GRB10 methylation is also correlated with genes involved in reactive oxygen species signaling, stress signaling and oxygen sensing and more recent data implicate GRB10 in insulin signaling. CONCLUSIONS: Single time point measurements of gene expression may reflect many factors unrelated to birth weight, while inter-individual differences in DNA methylation may represent a "molecular fossil record" of differences in birth weight-related gene expression. Finding these "unexpected" pathways may tell us something about the long-term association between low birth weight and adult disease, as well as which genes may be susceptible to environmental effects. These findings increase our understanding of the molecular mechanisms involved in human development and disease progression.

Explaining inter-individual variability in phenotype: is epigenetics up to the challenge?

The hypothesis that environmental factors alter somatically heritable epigenetic marks and change long-term patterns of gene expression is an exciting possibility in human disease research. Because most common diseases, and many quantitative traits, are influenced by both genetic and environmental factors, environmentally induced changes in epigenetic structures can provide a mechanistic link between genes and environment. We believe that inter-individual differences in the epigenetic modification of genes will explain a much greater fraction of inter-individual phenotypic variation than differences in genotype, alone.