Integrative network analysis of differentially methylated regions to study the impact of gestational weight gain on maternal metabolism and fetal-neonatal growth.

Integrative network analysis (INA) is important for identifying gene modules or epigenetically regulated molecular pathways in diseases. This study evaluated the effect of excessive gestational weight gain (EGWG) on INA of differentially methylated regions, maternal metabolism and offspring growth. Brazilian women from "The Araraquara Cohort Study" with adequate pre-pregnancy body mass index were divided into EGWG (n=30) versus adequate gestational weight gain (AGWG, n=45) groups. The methylome analysis was performed on maternal blood using the Illumina MethylationEPIC BeadChip. Fetal-neonatal growth was assessed by ultrasound and anthropometry, respectively. Maternal lipid and glycemic profiles were investigated. Maternal triglycerides-TG (p=0.030) and total cholesterol (p=0.014); fetus occipito-frontal diameter (p=0.005); neonate head circumference-HC (p=0.016) and thoracic perimeter (p=0.020) were greater in the EGWG compared to the AGWG group. Multiple linear regression analysis showed that maternal DNA methylation was associated with maternal TG and fasting insulin, fetal abdominal circumference, and fetal and neonate HC. The DMRs studied were enriched in 142 biological processes, 21 molecular functions,and 17 cellular components with terms directed for the fatty acids metabolism. Three DMGMs were identified:COL3A1, ITGA4 and KLRK1. INA targeted chronic diseases and maternal metabolism contributing to an epigenetic understanding of the involvement of GWG in maternal metabolism and fetal-neonatal growth.

Expression of candidate genes for residual feed intake in tropically adapted Bos taurus and Bos indicus bulls under thermoneutral and heat stress environmental conditions.

The objectives of this study were to measure the relative expression of the ATP1A1, NR3C1, POMC, NPY, and LEP genes in Caracu (Bos taurus) and Nelore (Bos indicus) bulls submitted to feed efficiency tests at high environmental temperatures, and to evaluate differences in adaptability to tropical conditions between breeds. Thirty-five Caracu and 30 Nelore bulls were submitted to a feed efficiency test using automated feeding stations. At the end of the test, the animals were subjected to thermoneutral (TN) and heat stress (HS) conditions. Blood samples were collected after the exposure to the TN and HS conditions and the relative expression of genes was measured by qPCR. The bulls exhibited lower expression of ATP1A1 in the HS condition than in the TN condition (1.98 ± 0.27 and 2.86 ± 0.26, P = 0.02), while the relative expression of NR3C1, POMC, and LEP did not differ (P > 0.05) between climatic conditions. The breed and feed intake influenced NPY and LEP expression levels (P < 0.05). Different climate conditions associated with residual feed intake can modify the gene expression patterns of ATP1A1 and NPY. The association observed among all genes studied shows that they are involved in appetite control. Bos taurus and Bos indicus bulls exhibited similar adaptability to tropical climate conditions.

Meiotic wave adds extra asymmetry to the development of female chicken gonads.

Development of female gonads in the chicken is asymmetric. This asymmetry affects gene expression, morphology, and germ cell development; consequently only the left ovary develops into a functional organ, whereas the right ovary remains vestigial. In males, on the other hand, both gonads develop into functional testes. Here, we revisited the development of asymmetric traits in female (and male) chicken gonads between Hamburger Hamilton stage 16 (HH16) and hatching. At HH16, primordial germ cells migrated preferentially to the left gonad, accumulating in the left coelomic hinge between the gut mesentery and developing gonad in both males and females. Using the meiotic markers SYCP3 and phosphorylated H2AFX, we identified a previously undescribed, pronounced asymmetryc meiotic progression in the germ cells located in the central, lateral, and extreme cortical regions of the left female gonad from HH38 until hatching. Moreover, we observed that--in contrast to the current view--medullary germ cells are not apoptotic, but remain arrested in pre-leptotene until hatching. In addition to the systematic analysis of the asymmetric distribution of germ cells in female chicken gonads, we propose an updated model suggesting that the localization of germ cells--in the left or right gonad; in the cortex or medulla of the left gonad; and in the central part or the extremities of the left cortex--has direct consequences for their development and participation in adult reproduction.

Excessive Gestational Weight Gain Alters DNA Methylation and Influences Foetal and Neonatal Body Composition.

BACKGROUND: Changes in body weight are associated with the regulation of DNA methylation (DNAm). In this study, we investigated the associations between maternal gestational weight gain-related DNAm and foetal and neonatal body composition. METHODS: Brazilian pregnant women from the Araraquara Cohort Study were followed up during pregnancy, delivery, and after hospital discharge. Women with normal pre-pregnancy BMI were allocated into two groups: adequate gestational weight gain (AGWG, n = 45) and excessive gestational weight gain (EGWG, n = 30). Foetal and neonatal body composition was evaluated via ultrasound and plethysmography, respectively. DNAm was assessed in maternal blood using Illumina Infinium MethylationEPIC BeadChip arrays. Linear regression models were used to explore the associations between DNAm and foetal and neonatal body composition. RESULTS: Maternal weight, GWG, neonatal weight, and fat mass were higher in the EGWG group. Analysis of DNAm identified 46 differentially methylated positions and 11 differentially methylated regions (DMRs) between the EGWG and AGWG groups. Nine human phenotypes were enriched for these 11 DMRs located in 13 genes (EMILIN1, HOXA5, CPT1B, CLDN9, ZFP57, BRCA1, POU5F1, ANKRD33, HLA-B, RANBP17, ZMYND11, DIP2C, TMEM232), highlighting the terms insulin resistance, and hyperglycaemia. Maternal DNAm was associated with foetal total thigh and arm tissues and subcutaneous thigh and arm fat, as well as with neonatal fat mass percentage and fat mass. CONCLUSION: The methylation pattern in the EGWG group indicated a risk for developing chronic diseases and involvement of maternal DNAm in foetal lean and fat mass and in neonatal fat mass.

The relationship between obesity-related H19DMR methylation and H19 and IGF2 gene expression on offspring growth and body composition.

Background and objective: Imprinted genes are important for the offspring development. To assess the relationship between obesity-related H19DMR methylation and H19 and IGF2 gene expression and offspring growth and body composition. Methods: Thirty-nine overweight/obese and 25 normal weight pregnant women were selected from the "Araraquara Cohort Study" according to their pre-pregnancy BMI. Fetal growth and body composition and newborn growth were assessed, respectively, by ultrasound and anthropometry. The methylation of H19DMR in maternal blood, cord blood, maternal decidua and placental villi tissues was evaluated by methylation-sensitive restriction endonuclease qPCR, and H19 and IGF2 expression by relative real-time PCR quantification. Multiple linear regression models explored the associations of DNA methylation and gene expression with maternal, fetal, and newborn parameters. Results: H19DMR was less methylated in maternal blood of the overweight/obese group. There were associations of H19DMR methylation in cord blood with centiles of fetal biparietal diameter (BPD) and abdominal subcutaneous fat thickness and newborn head circumference (HC); H19DMR methylation in maternal decidua with fetal occipitofrontal diameter (OFD), HC, and length; H19DMR methylation in placental villi with fetal OFD, HC and abdominal subcutaneous fat thickness and with newborn HC. H19 expression in maternal decidua was associated with fetal BPD and femur length centiles and in placental villi with fetal OFD and subcutaneous arm fat. IGF2 expression in maternal decidua was associated with fetal BPD and in placental villi with fetal OFD. Conclusion: To our knowledge, this is the first study to demonstrate associations of imprinted genes variations at the maternal-fetal interface of the placenta and in cord blood with fetal body composition, supporting the involvement of epigenetic mechanisms in offspring growth and body composition.

Global genomic methylation related to the degree of parasitism in cattle.

The objective of the present study was to characterize a herd of 72 ½ Angus × ½ Nellore heifers, identify the resistant, resilient and susceptible animals to parasites, relate the overall DNA methylation of these animals with the degree of parasitism, evaluated by the egg count per gram of feces (EPG), Haematobia irritans count (horn fly) and Rhipicephalus microplus count (bovine tick). The experiment was carried out in a completely randomized design, containing 72 treatments, with each animal considered a treatment, and 11 repetitions, with each collection within a year considered a repetition. The data obtained from the counts of the evaluated parasites were subjected to statistical analysis using the SISVAR program, to classify heifers according to the degree of parasitism in low (resistant), intermediary (resilient) and high (susceptible) parasite load for infection by nematodes, infestation by ticks and flies. Addition the animals in these three groups, by hierarchical grouping using the GENES program, heifers were classified as to the degree of parasitism by the three parasites along with the DNA methylation content of the animals in each group. A negative relationship was observed between resistance and methylated DNA content in both classifications, with the resistant, resilient, and susceptible animals showing the highest, intermediate, and lowest methylated DNA quantifications, respectively. Thus, the methodologies used herein enabled the classification of 72 heifers according to the degree of collective infection by gastrointestinal nematodes and infestation by ticks and horn flies, thereby establishing a link between the degree of parasitic resistance in cattle and the global methylated DNA quantification.

Generation of Primordial Germ Cell-like Cells from iPSCs Derived from Turner Syndrome Patients.

Turner syndrome (TS) is a genetic disorder in females with X Chromosome monosomy associated with highly variable clinical features, including premature primary gonadal failure leading to ovarian dysfunction and infertility. The mechanism of development of primordial germ cells (PGCs) and their connection with ovarian failure in TS is poorly understood. An in vitro model of PGCs from TS would be beneficial for investigating genetic and epigenetic factors that influence germ cell specification. Here we investigated the potential of reprogramming peripheral mononuclear blood cells from TS women (PBMCs-TS) into iPSCs following in vitro differentiation in hPGCLCs. All hiPSCs-TS lines demonstrated pluripotency state and were capable of differentiation into three embryonic layers (ectoderm, endoderm, and mesoderm). The PGCLCs-TS recapitulated the initial germline development period regarding transcripts and protein marks, including the epigenetic profile. Overall, our results highlighted the feasibility of producing in vitro models to help the understanding of the mechanisms associated with germ cell formation in TS.

Oral Rehabilitation of a Child with Hypohidrotic Ectodermal Dysplasia.

Hypohidrotic ectodermal dysplasia (HED) is a genetic condition characterized by abnormal development of two or more structures of the ectoderm, such as skin, hair, nails, teeth, or sweat glands. The most common dental anomalies are oligodontia and anodontia but taurodontism has also been described. These patients present a decrease of alveolar bone volume and alveolar ridge tapering due to congenitally missing teeth. The purpose of this report is to describe the case of a six-year-old girl diagnosed with HED who presented with conical teeth, taurodontic molars, and multiple agenesis that decreased the patient's self-esteem and social interactions. The proposed treatment was to accomplish an oral rehabilitation that was functional, provided the patient with the ability for correct mastication, good esthetics, and comfort, using restorations and devices that did not interfere with the child's orofacial growth and development. (J Dent Child 2019;86(3):158-63).

Variation in DNA methylation in the KvDMR1 (ICR2) region in first-trimester human pregnancies.

OBJECTIVE: To investigate the levels of DNA methylation in the KvDMR1 (KvLQT1 differentially methylated region 1) in embryonic and extra-embryonic tissues. DESIGN: Cross-sectional study. SETTING: University medical center and clinical hospital. PATIENT(S): Embryonic and/or extraembryonic tissues (umbilical cord, chorionic villus, chorion, decidua, and/or amnion) collected from 27 first-trimester pregnancies (up to 12 weeks of gestation, single embryos) from elective abortions, extravillous trophoblasts (EVTs) from the top of individual chorionic villi, and chorionic villi from 10 normal full-term placentas collected after birth. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): DNA methylation of the KvDMR1 region evaluated using quantitative analysis of DNA methylation followed by real-time polymerase chain reaction (qAMP) and bisulfite sequencing (bis-seq) analysis. RESULT(S): The results showed variability in KvDMR1 DNA methylation in different tissues from the same pregnancy. The average of DNA methylation was not different between the embryo, umbilical cord, amnion, and chorionic villi, despite the relatively low level of methylation observed in the amnion (33.50% ± 14.48%). Chorionic villi from term placentas showed a normal methylation pattern at KvDMR1 (42.60% ± 6.08%). The normal methylation pattern at KvDMR1 in chorionic villi (as well as in EVTs) from first-trimester placentas was confirmed by bis-seq. CONCLUSION(S): Our results highlight an existing heterogeneity in DNA methylation of the KvDMR1 region during first trimester and a consistent hypomethylation in the amnion in this period of gestation.

The relationship among sperm global DNA methylation, telomere length, and DNA fragmentation in varicocele: a cross-sectional study of 20 cases.

Varicocele pathophysiology is related to increased oxidative stress, which might result in loss sperm DNA integrity as well as in genomic instability. Sperm telomere shortening and loss of global DNA methylation are the main features of genomic instability, leading to cell senescence and death, whereas sperm DNA fragmentation (SDF) characterizes the loss of chromatin integrity. We hypothesize that sperm genomic stability and DNA integrity is reduced in infertile men with moderate and large-sized varicoceles, thus being candidate markers of sperm quality in varicocele-related infertility. Here, we assessed the sperm global DNA methylation, telomere length, and SDF in men with and without clinically palpable varicoceles. While the rates of SDF and telomere length were not statistically different between varicocele patients and controls, global sperm DNA methylation seems to be lower in men with varicocele (49.7% ± 20.7%) than controls (64.7% ± 17.1%). A negative correlation between SDF and sperm motility and a positive correlation between sperm morphology and telomere length were observed. Our results suggest that varicocele may result in genomic instability, in particular, global DNA hypomethylation. However, a large sample size may confirm these findings. The understanding of the molecular mechanisms involved in the pathophysiology of varicocele-related infertility may help to better select candidates for varicocele repair.

A new chicken molecular sexing assay based on the Z chromosome dose and the MHM region.

Birds have a ZZ and ZW sex chromosome system (male and female, respectively). On the short arm of the Z chromosome of Gallus gallus domesticus there is a repetitive region called MHM region, which is absent on the W chromosome, that causes a natural copy number difference of the MHM region between the sexes, making possible the development of a quantitative PCR (qPCR) sexing assay, based on the Z chromosome double dose. Twenty-seven samples of tissues from eight adult Gallus gallus domesticus (four males and four females) were used to establish the parameters of the MHM copy-number sexing assay. We blinded sexed 20 chicks using 140 samples from different tissues (heart, brain, gonad, kidney, lung, muscle, and blood). The success rate of the assay was 100% (140/140). It required small amounts of DNA (0.39 ng), opening the perspective to the use of the assay in studies in which the amount of available DNA is limited.

Turner syndrome: counseling prior to oocyte donation.

Ovarian failure is a typical feature of Turner syndrome (TS). Patients are followed clinically with hormone replacement therapy (HRT) and inclusion in the oocyte donation program, if necessary. For patients with spontaneous puberty, genetic counseling regarding preimplantation genetic diagnosis and prenatal diagnosis is indicated. Patients with dysgenetic gonads and a Y chromosome are at increased risk of developing gonadoblastoma. Even though this is not an invasive tumor, its frequent association with other malignant forms justifies prophylactic gonadectomy. It is important to perform gonadectomy before HRT and pregnancy with oocyte donation. Among patients with TS stigmata and female genitalia, many have the Y chromosome in one of the cell lines. For this reason, all patients should undergo cytogenetic analysis. Nevertheless, in cases of structural chromosomal alterations or hidden mosaicism, the conventional cytogenetic techniques may be ineffective and molecular investigation is indicated. The author proposes a practical approach for investigating women with TS stigmata in whom identification of the X or Y chromosome is important for clinical management and follow-up.

Atendendo mulheres com cariótipo 46, XY / Attending women with 46, XY karyotype

As diferenças ou distúrbios do desenvolvimento sexual (DDS) compreendem um grupo heterogêneo de condições congênitas que resultam na discordância entre os cromossomos sexuais, as gônadas e/ou o sexo anatômico de um indivíduo. A classificação desses distúrbios é baseada no cariótipo conforme o Consenso de Chicago de 2006 e substitui os termos pseudo-hermafroditismo, hermafroditismo e intersexo. O objetivo desta revisão é fornecer ao ginecologista conhecimentos básicos sobre a etiologia, fisiopatologia e orientações das principais anormalidades de DDS para uma avaliação diagnóstica e terapêutica no atendimento de mulheres na infância, adolescência e em idade adulta com cariótipo 46,XY. O diagnóstico deve ser realizado pela interação entre o exame clínico as dosagens hormonais, os exames de imagem e a análise genética, desde o cariótipo até o estudo de alterações dos genes por técnicas de biologia molecular. O tratamento é realizado de acordo com a etiologia e inclui intervenções cirúrgicas como a gonadectomia e plásticas sobre a genitália externa, terapia de reposição hormonal e apoio psicológico. São necessárias a individualização dos casos e uma equipe interdisciplinar, para um atendimento adequado às mulheres com cariótipo 46,XY.(AU)

Differences or disorders of sexual development (DSDs) comprise a heterogeneous group of congenital conditions that result in the disagreement between an individual's sex chromosomes, gonads and/or anatomic sex. The classification of these disorders is based on the karyotype according to the 2006 Chicago Consensus and replaces the terms pseudohermaphroditism, hermaphroditism and intersex. The aim of this review is to provide the gynecologist with basic knowledge about the etiology, pathophysiology and guidelines of the main abnormalities of DDS for a diagnostic and therapeutic evaluation in the care of women in childhood, adolescence and adulthood with a karyotype 46,XY. The diagnosis must be made by the interaction between clinical examination hormonal measurements, imaging and genetic analysis from the karyotype to the study of gene alterations by molecular biology techniques. Treatment is carried out according to the etiology and includes surgical interventions such as gonadectomy and plastic surgery on the external genitalia, hormone replacement therapy and psychological support. Individualization of cases and an interdisciplinary team are required to provide adequate care for women 46,XY karyotype.(AU)

Cell-free fetal DNA in maternal plasma and noninvasive prenatal diagnosis.

The noninvasive nature of the detection of fetal DNA in the maternal circulation represents the greatest advantage over the conventional methods of prenatal diagnosis. The applications of this methodology involve the detection of the fetal sex, and diagnosis, intra-uterine treatment, and evaluation of the prognosis of many diseases. Fetal cells detected in the maternal circulation have also been shown to be implicated in autoimmune diseases and to represent a potential source of stem cells. On the other hand, with the introduction of a technology that detects the fetal sex as early as at 6-8 weeks of gestation, there is the possibility of early abortion based on sex selection for social purposes. This implies an ethical discussion about the question. The introduction of new noninvasive techniques of prenatal diagnosis and the knowledge of the Nursing Team regarding new methodologies can be of great benefit to the mother and her children, and can help the Genetic Counseling of the families.

Genomic-based nursing care for women with Turner Syndrome: genomic-based nursing care.

Biologic and technologic advances generated from The Human Genome Project are having a dramatic impact on the expanding role of nurses in current health care practice. New genetic research needs to be transformed rapidly into clinical protocols with recommendations for delivering care to targeted populations. Nurses can contribute significantly, as part of an interdisciplinary approach, to translate genome-based knowledge into benefits for health care and society. In this context, we describe a clinical-genetic investigation protocol, as well nursing diagnosis, interventions and outcomes for clients with Turner Syndrome (TS) at risk for develop gonadal tumors, due the presence of a normal or abnormal Y chromosome.

Familial chromosomal translocation X; 22 associated with infertility and recurrent X mosaicism.

BACKGROUND: Individuals with apparently balanced translocations, often, show no clinical findings. However, in meiosis, translocations tend to cause errors on chromosome disjunction and the ones involving sex chromosomes have particular implications for the phenotype. Male carriers of balanced X-autosome translocations are almost invariably infertile due to interruption of the spermatogenesis, but the mechanism is not fully understood. CASE PRESENTATION: In this case report, we performed a combination of classical cytogenetics (G-banding), molecular cytogenetics (fluorescence in situ hybridization and X-chromosome inactivation study), and cytogenomics (microarray-based comparative genomic hybridization) techniques for characterization of an inherited (X;22) translocation in a family originally referred for infertility investigation. Both proband and his sister are infertile and present the maternally inherited translocation. Interestingly, the maternal grandmother was mosaic for X chromosome monosomy suggesting that the t(X;22) in the proband's mother arose by errors at oogenesis. The presence of the same mosaicism of the X chromosome in the proband's aunt is consistent with this consideration. Array- CGH analysis showed no constitutional pathogenic gains or losses in the translocation carriers. The X-chromosome inactivation studies revealed that the translocated X;22 was active in 99.3% of cells in the mother and in 88% of cells in the daughter. We suggest that incomplete skewing of X inactivation (>97 %) of the daughter could justify the infertility. This study is the first description of recurrent mosaicism of the X chromosome associated with a familial X-autosome translocation. CONCLUSIONS: The phenotype of infertility was probably caused by disruption of spermatogenesis due to gametogenesis specific errors resulted from meiotic pairing and segregation anomalies on the translocated chromosomes.

Erratum to: Familial chromosomal translocation X; 22 associated with infertility and recurrent X mosaicism.

[This corrects the article DOI: 10.1186/s13039-016-0249-5.].

Alterações cromossômicas e periostite / Chromosomal alterations and periostitis

Introdução: A periostite é uma inflamação do periósteo que pode se estender para os tecidos moles adjacentes. Há pouca informação na literatura sobre alterações genéticas nessas lesões, as quais são reparadas por intensas reações de proliferação osteoblástica e possuem curso clínico semelhante ao das osteomielites crônicas inespecíficas, que podem evoluir para neoplasias. Objetivo: análise citogenética de amostra de periostite para detecção e descrição de alterações cromossômicas, principalmente as associadas com desenvolvimento de neoplasias. Métodos: material obtido de lesão em palato de paciente, um homem de 74 anos de idade, submetido anteriormente a cirurgias de remoção de carcinoma basocelular em nariz e cavidade oral. Após a coleta, com estudo histopatológico confirmando apenas material de periostite, a amostra foi submetida à análise citogenética a partir de cultura de células e bandamento GTG. Resultados: o cariótipo composto evidenciou, como alterações clonais, monossomia dos cromossomos 10, 15, 20 e 22; trissomia do cromossomo 22; inversão do cromossomo 12 e deleção de 15q. O grande número de alterações cromossômicas estaria relacionado com a alta taxa de proliferação celular, a qual poderia induzir replicação celular desbalanceada e instabilidade genética. Há genes, envolvidos com desenvolvimento de neoplasias, localizados nos pontos de quebra das alterações estruturais encontradas nos cromossomos 12 e 15. Conclusão: foram evidenciadas várias alterações cromossômicas que refletiriam a proliferação celular local. A análise citogenética em casos de periostite poderá auxiliar na descoberta de biomarcadores de prognóstico e ser utilizada, futuramente, na rotina médica para um melhor manejo dos pacientes.

Introduction: Periostitis is an inflammation of the soft tissues adjacent to the bone that affects the periosteum. There is little information in the literature about genetic alterations in these lesions, which are repaired by intense osteoblast proliferation reactions and present a clinical course that resembles that of nonspecific chronic osteomyelitis that may progress to neoplasms. Objective: Cytogenetic analysis of periostitis sample for detection and description of chromosomal alterations, especially those associated with cancer development. Methods: Material obtained from a palate lesion of a 74-year-old man who had previously undergone surgery to remove basal cell carcinoma in the nose and oral cavity. After collection, with a histopathological study confirming only periostitis material, the sample was submitted to a cytogenetic analysis from cell culture and GTG banding. Results: The composite karyotype showed, as clonal alterations, monosomy of chromosomes 10, 15, 20, and 22; trisomy of chromosome 22; inversion of chromosome 12, and deletion of 15q. The large number of chromosomal alterations would be related to the high rate of cell proliferation, which could induce unbalanced cell replication and genetic instability. There are genes, which are involved in the development of neoplasms, mapped at the breakpoints of structural changes found on chromosomes 12 and 15. Conclusion: Several chromosomal alterations that were observed would reflect local cell proliferation. Cytogenetic analysis of periostitis may help in the discovery of prognostic biomarkers and may be used in the medical routine for better patient management in the future.

Beckwith-Wiedemann syndrome and isolated hemihyperplasia.

CONTEXT: Beckwith-Wiedemann syndrome is a complex and heterogeneous overgrowth syndrome with genetic and epigenetic alterations, involving genomic imprinting and cancer predisposition. Isolated hemihyperplasia is of unknown cause, and it may represent a partial or incomplete expression of Beckwith-Wiedemann syndrome. OBJECTIVES: A clinical and molecular review and proposal of the use of an experimental protocol to provide a practical approach for the physician. DATA SYNTHESIS: This review demonstrates the genetic and epigenetic mechanisms involved in the Beckwith-Wiedemann syndrome and isolated hemihyperplasia, and the candidate genes. To our knowledge, this is the first Brazilian protocol for research into these disorders. The results have been used at the Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, to elucidate the basis of Beckwith-Wiedemann syndrome and isolated hemihyperplasia, and have been applied at the Hospital Universitário of the Faculdade de Medicina. CONCLUSIONS: Elucidation of the etiological mechanisms and use of a laboratory protocol to detect alterations in these disorders may be useful for guiding the management of such patients and genetic counseling of the families.

5meCpG epigenetic marks neighboring a primate-conserved core promoter short tandem repeat indicate X-chromosome inactivation.

X-chromosome inactivation (XCI) is the epigenetic transcriptional silencing of an X-chromosome during the early stages of embryonic development in female eutherian mammals. XCI assures monoallelic expression in each cell and compensation for dosage-sensitive X-linked genes between females (XX) and males (XY). DNA methylation at the carbon-5 position of the cytosine pyrimidine ring in the context of a CpG dinucleotide sequence (5meCpG) in promoter regions is a key epigenetic marker for transcriptional gene silencing. Using computational analysis, we revealed an extragenic tandem GAAA repeat 230-bp from the landmark CpG island of the human X-linked retinitis pigmentosa 2 RP2 promoter whose 5meCpG status correlates with XCI. We used this RP2 onshore tandem GAAA repeat to develop an allele-specific 5meCpG-based PCR assay that is highly concordant with the human androgen receptor (AR) exonic tandem CAG repeat-based standard HUMARA assay in discriminating active (Xa) from inactive (Xi) X-chromosomes. The RP2 onshore tandem GAAA repeat contains neutral features that are lacking in the AR disease-linked tandem CAG repeat, is highly polymorphic (heterozygosity rates approximately 0.8) and shows minimal variation in the Xa/Xi ratio. The combined informativeness of RP2/AR is approximately 0.97, and this assay excels at determining the 5meCpG status of alleles at the Xp (RP2) and Xq (AR) chromosome arms in a single reaction. These findings are relevant and directly translatable to nonhuman primate models of XCI in which the AR CAG-repeat is monomorphic. We conducted the RP2 onshore tandem GAAA repeat assay in the naturally occurring chimeric New World monkey marmoset (Callitrichidae) and found it to be informative. The RP2 onshore tandem GAAA repeat will facilitate studies on the variable phenotypic expression of dominant and recessive X-linked diseases, epigenetic changes in twins, the physiology of aging hematopoiesis, the pathogenesis of age-related hematopoietic malignancies and the clonality of cancers in human and nonhuman primates.