Comparison of clinical characteristics of a pediatric cohort with combined pituitary hormone deficiency caused by mutation of the PROP1 gene or of other origins.

The most commonly identified genetic cause of combined pituitary hormone deficiency (CPHD) is PROP1 gene mutations. The aim of the study was to compare selected clinical features of patients with CPHD caused by variants of the PROP1 gene (CPHD-PROP1) and patients with inborn CPHD of other etiology (CPHD-nonPROP1). MATERIAL AND METHODS: The retrospective analysis included childhood medical records of 74 patients (32 female) with CPHD, including 43 patients (23 female) with the mutation in the PROP1 gene. RESULTS: Patients with CPHD-PROP1 compared to the CPHD-nonPROP1 presented with the following: significantly higher median birth weight (0.21 vs. - 0.29 SDS, p = 0.019), lower growth velocity within 3 years preceding growth hormone administration (- 2.7 vs. - 0.8 SDS, p < 0.001), higher mean maximal blood concentration of growth hormone within the stimulation process (1.2 vs. 1.08 ng/mL, p = 0.003), lower TSH (1.8 vs. 2.4 µIU/mL, p < 0.001), significantly lower prolactin concentrations (128 vs. 416.3 µIU/mL, p < 0.001), and less frequent typical signs of hypogonadism at birth in boys (n = 6; 30% vs. n = 12, 54%, p < 0.001). Secondary adrenal insufficiency was less frequent in CPHD-PROP1 (20 vs. 25 cases, p = 0.006) and occurred at a later age (13.4 vs. 10.4 years). MRI of the pituitary gland in CPHD-PROP1 revealed a small pituitary gland (21 cases), pituitary gland enlargement (eight cases), and one pituitary stalk interruption and posterior lobe ectopy, while it was normal in nine cases. CONCLUSION: Patients with the PROP1 mutations present a clinical picture significantly different from that of other forms of congenital hypopituitarism. Certain specific clinical results may lead to the successful identification of children requiring diagnostics for the PROP1 gene mutation.

Analysis of miRNAs in Osteogenesis imperfecta Caused by Mutations in COL1A1 and COL1A2: Insights into Molecular Mechanisms and Potential Therapeutic Targets.

Osteogenesis imperfecta (OI) is a group of connective tissue disorders leading to abnormal bone formation, mainly due to mutations in genes encoding collagen type I (Col I). Osteogenesis is regulated by a number of molecules, including microRNAs (miRNAs), indicating their potential as targets for OI therapy. The goal of this study was to identify and analyze the expression profiles of miRNAs involved in bone extracellular matrix (ECM) regulation in patients diagnosed with OI type I caused by mutations in COL1A1 or COL1A2. Primary skin fibroblast cultures were used for DNA purification and sequence analysis, followed by analysis of miRNA expression. Sequencing analysis revealed mutations of the COL1A1 or COL1A2 genes in all OI patients, including four previously unreported. Amongst the 40 miRNAs analyzed, 9 were identified exclusively in OI cells and 26 in both OI patients and the controls. In the latter case, the expression of six miRNAs (hsa-miR-10b-5p, hsa-miR-19a-3p, hsa-miR-19b-3p, has-miR-204-5p, has-miR-216a-5p, and hsa-miR-449a) increased, while four (hsa-miR-129-5p, hsa-miR-199b-5p, hsa-miR-664a-5p, and hsa-miR-30a-5p) decreased significantly in OI cells in comparison to their expression in the control cells. The identified mutations and miRNA expression profiles shed light on the intricate processes governing bone formation and ECM regulation, paving the way for further research and potential therapeutic advancements in OI and other genetic diseases related to bone abnormality management.

Clinical, genetic, and epidemiological survey of Polish children and adolescents with severe obesity: A study protocol of the Polish-German study project on severe early-onset obesity.

Severe early-onset obesity (SEOO) in children is a common feature of monogenic obesity. Nowadays, mutations in at least 50 genes are known to be related to monogenic obesity, and many others are tested. Part of them is involved in the leptin-proopiomelanocortin pathway. The aim of the project is to establish the Polish database of severely obese children and adolescents and to evaluate the prevalence of monogenic forms of obesity in this cohort, with a special focus on leptin-proopiomelanocortin pathway abnormalities. The secondary project aim is to identify new population-specific mutations in obesity-related genes in severely obese Polish children and adolescents. This is a prospective multi-center clinical study performed in four Polish centers. The estimated sample size is 500 patients aged 1-18 years, with severe obesity, hyperphagia, and food-seeking behaviors. In each patient, the medical history regarding the obesity duration in the patient and obesity and its complication existence in the family will be taken. Next, the questionnaire regarding the symptom characteristic of specific mutations, which we are going to test, will be performed. Hyperphagia will be assessed on the basis of age-specific questionnaires. The physical examination with anthropometric measurement, basic biochemical and hormonal tests, and leptin and biologically active leptin measurements will be performed. Finally, genetic analysis will be performed using next-generation sequencing with sequencing libraries prepared to include obesity-related genes. The genotyping findings will be confirmed with the use of classic sequencing (Sanger's method). In the future, the pathogenicity of new mutations in obesity-related genes identified in our cohort is planned to be confirmed by functional testing in vitro. Nowadays, there are no data regarding the prevalence of severe obesity or monogenic obesity in Polish children. This project has the potential to improve understanding of obesity etiology and may contribute to implementing attribute mutation-specific treatment. Moreover, it may lead to a finding of new, population-specific mutations related to SEOO.

Cardiovascular Anomalies among 1005 Fetuses Referred to Invasive Prenatal Testing-A Comprehensive Cohort Study of Associated Chromosomal Aberrations.

This retrospective cohort study comprehensively evaluates cardiovascular anomalies (CVAs) and associated extracardiac structural malformations (ECMs) among 1005 fetuses undergoing invasive prenatal testing at a single tertiary Polish center in the context of chromosomal aberrations detected in them by array comparative genomic hybridization (aCGH) and G-band karyotyping. The results of our study show that CVAs are among the most common malformations detected in fetuses undergoing invasive prenatal testing, as they affected 20% of all cases seen in our department. Septal defects predominated among fetuses with numerical aberrations, while conotruncal defects were the most common findings among fetuses with pathogenic copy number variants (CNVs). In 61% of cases, CVAs were associated with ECMs (the diagnosis was confirmed postnatally or in cases of pregnancy termination by means of autopsy). The most common ECMs were anomalies of the face and neck, followed by skeletal defects. In total, pathogenic chromosomal aberrations were found in 47.5% of CVAs cases, including 38.6% with numerical chromosomal aberrations. Pathogenic CNVs accounted for 14.5% of cases with CVAs and normal karyotype. Thus, our study highlights the importance of assessing the anatomy of the fetus, and of the genetic testing (preferably aCGH) that should be offered in all CVA and ECM cases.

Genetic Profiling in Children With Acute Lymphoblastic Leukemia Referred for Allogeneic Hematopoietic Stem Cell Transplantation.

INTRODUCTION: Hematopoietic stem cell transplantation (HSCT) is the essential and often the only curative therapeutic option in high risk and relapsed pediatric acute lymphoblastic leukemia (ALL). METHODS: The objective of the study was to investigate whole-genome expression in children with high risk or relapsed ALL referred for HSCT. Gene expression was assessed in 18 children with ALL referred for HSCT (10 high risk, 8 relapsed; median age of 9.4 years) and in a control group of 38 obese children (median age of 14.1 years). Whole-genome expression was assessed in leukocytes using GeneChip® HumanGene 1.0 ST microarray. RESULTS: The analysis of genomic profiles revealed a significantly lower expression of 21 genes with a defined function, involved in immunoglobulin production, lymphocyte function, or regulation of DNA processing in ALL patients referred for HSCT compared with the control group. CONCLUSION: Genome expression of patients with ALL in remission referred to HSCT revealed deep immunosuppression of both B-cell and T-cell lineages, which may increase the probability of donor cell engraftment.

Management precautions for risk of obesity are necessary among infants with PKU carrying the rs113883650 variant of the LAT1 gene: A cross-sectional study.

Patients with phenylketonuria (PKU), an inborn error of phenylalanine metabolism, require consistent treatment to avoid the brain toxicity caused by hyperphenylalaninemia. The treatment consists of life-long use of a low-phenylalanine diet, which aims at decreasing hyperphenylalaninemia and maintaining blood phenylalanine concentration in a safe range. Problems with balancing diet can result in suboptimal treatment outcomes; however, recent findings suggest that genetic alteration of the transport of phenylalanine might result in an additional health burden. We assessed the effect of a common variant (rs113883650) of the LAT1(SLC7A5) gene, which encodes the main transmembrane phenylalanine transporter, on the development of overweight in 54 infants with PKU who received standard therapy and adhered well to therapeutic prescriptions, and in 55 infants with a milder disease form-the so-called mild hyperphenylalaninemia (MHP), which does not require treatment. We found that infants with PKU-carriers of the rs113883650 variant had significantly higher Body Mass Index (BMI) at 1 year compared to PKU infants without the variant (mean BMI Z-Score of +1.15 SD vs -0.15 SD, respectively; t(52) = 5.25, p = 0.00005). Conversely, no significant BMI differences were detected in the subgroups of infants with MHP (t(53) = 1.15, p = 0.25). Additionally, high BMI in infants with PKU-carriers of the rs113883650 variant positively correlated with high variability of their blood phenylalanine levels (r(52) = 0.42, p = 0.002). It should be noted that this is an observational study, which does not determine causation. Nevertheless, our findings show that the rs113883650 variant of the LAT1 gene may be a risk factor for overweight in properly treated infants with PKU. Management precautions should be taken to prevent the development of overweight and obesity.

Concentrations of Insulin-like Growth Factors and Insulin-like Growth Factor-Binding Proteins and Respective Gene Expressions in Children before and after Hematopoietic Stem Cell Transplantation.

Insulin-like growth factors (IGF-1 and IGF-2) and insulin-like growth factor-binding proteins (IGFBP-1 to -7) are involved in the regulation of cell proliferation and differentiation and may be associated with various metabolic parameters. The aim of our study was to compare levels of IGFs and IGFBPs and the expressions of their genes in children before and after hematopoietic stem cell transplantation (HSCT) to assess their potential as markers of late metabolic complications of HSCT. We also conducted additional comparisons with healthy controls and of correlations of IGF and IGFBP levels with anthropometric and biochemical parameters. We analyzed 19 children treated with HSCT and 21 healthy controls. We found no significant differences in the levels of IGFs and IGFBPs and expressions of their genes before and after HSCT, while IGF and IGFBP levels were significantly lower in children treated with HSCT compared with controls. We conclude that our results did not reveal significant differences between the levels of IGFs and IGFBPs before and after HSCT, which would make them obvious candidates for markers of late complications of the procedure in children. However, due to the very low number of patients this conclusion must be taken with caution and may be altered by further research.

COVID-19 Pandemic and Patients with Rare Inherited Metabolic Disorders and Rare Autoinflammatory Diseases-Organizational Challenges from the Point of View of Healthcare Providers.

COVID-19 pandemic is an organisational challenge for both healthcare providers and patients. People with rare inherited metabolic disorders (IMD) and rare autoinflammatory diseases (AD) are vulnerable patients whose well-being is deeply connected with regular follow-ups. This study aimed to assess how e one year of coronavirus pandemic has impacted the treatment of patients with IMD and AD in Poland. Surveys were distributed to all healthcare providers that coordinate the treatment of IMD and AD patients. Thirty-two responders (55%) answered the survey. They provide care to 1726 patients with IMD/AD, including 246 patients on dedicated treatment. In 35% of units, the regular appointments were disrupted, primarily because of patient infection. In 18 hospitals, remote visits were implemented, but only 66.6% of patients used this form of consultation. In 14/32 hospitals, administration of the therapy was delayed (median: 17.4 days). Forty-four patients suffered from SARS-COV-2 infection, in majority with mild symptoms. However, four adult patients developed complications, and one died following a SARS-COV-2 infection. Although most hospitals managed to maintain regular visits during the pandemic, more comprehensive implementation of telemedicine and switch to oral therapy or home infusions would be a reasonable solution for the current epidemic situation.

The Expression of Genes Related to Lipid Metabolism and Metabolic Disorders in Children before and after Hematopoietic Stem Cell Transplantation-A Prospective Observational Study.

Metabolic disorders in children after hematopoietic stem cell transplantation (HSCT) are poorly characterized. However, it is known that dyslipidemia and insulin resistance are particularly common in these patients. We conducted a prospective study of 27 patients treated with HSCT to assess the possibility of predicting these abnormalities. We measured gene expressions using a microarray technique to identify differences in expression of genes associated with lipid metabolism before and after HSCT. In patients treated with HSCT, total cholesterol levels were significantly higher after the procedure compared with the values before HSCT. Microarray analysis revealed statistically significant differences in expressions of three genes, DPP4, PLAG1, and SCD, after applying the Benjamini-Hochberg procedure (pBH < 0.05). In multiple logistic regression, the increase of DPP4 gene expression before HCST (as well as its change between pre- and post-HSCT status) was associated with dyslipidemia. In children treated with HSCT, the burden of lipid disorders in short-term follow-up seems to be lower than before the procedure. The expression pattern of DPP4 is linked with dyslipidemia after the transplantation.

Methylation and Expression of FTO and PLAG1 Genes in Childhood Obesity: Insight into Anthropometric Parameters and Glucose-Lipid Metabolism.

The occurrence of childhood obesity is influenced by both genetic and epigenetic factors. FTO (FTO alpha-ketoglutarate dependent dioxygenase) is a gene of well-established connection with adiposity, while a protooncogene PLAG1 (PLAG1 zinc finger) has been only recently linked to this condition. We performed a cross-sectional study on a cohort of 16 obese (aged 6.6-17.7) and 10 healthy (aged 11.4-16.9) children. The aim was to evaluate the relationship between methylation and expression of the aforementioned genes and the presence of obesity as well as alterations in anthropometric measurements (including waist circumference (WC), body fat (BF_kg) and body fat percent (BF_%)), metabolic parameters (lipid profile, blood glucose and insulin levels, presence of insulin resistance) and blood pressure. Expression and methylation were measured in peripheral blood mononuclear cells using a microarray technique and a method based on restriction enzymes, respectively. Multiple regression models were constructed to adjust for the possible influence of age and sex on the investigated associations. We showed significantly increased expression of the FTO gene in obese children and in patients with documented insulin resistance. Higher FTO expression was also associated with an increase in WC, BF_kg, and BF_% as well as higher fasting concentration of free fatty acids (FFA). FTO methylation correlated positively with WC and BF_kg. Increase in PLAG1 expression was associated with higher BF%. Our results indicate that the FTO gene is likely to play an important role in the development of childhood adiposity together with coexisting impairment of glucose-lipid metabolism.

The rs113883650 variant of SLC7A5 (LAT1) gene may alter brain phenylalanine content in PKU.

Functional alteration of the LAT1 amino acid transporter may be responsible for interindividual differences in cerebral phenylalanine content and the lack of intellectual disability in some patients with untreated phenylketonuria. We assessed the effect of the common variant rs113883650 of the SLC7A5 (LAT1) gene on brain phenylalanine content, as measured with use of magnetic resonance spectroscopy. Our results suggest that the presence of this variant could influence the amount of phenylalanine in the brain.

Developmental delay with hypotrophy associated with homozygous functionally relevant REV3L variant.

REV3L encodes a catalytic subunit of DNA polymerase zeta (Pol zeta) which is essential for the tolerance of DNA damage by inducing translesion synthesis (TLS). So far, the only Mendelian disease associated with REV3L was Moebius syndrome (3 patients with dominant REV3L mutations causing monoallelic loss-of-function were reported). We describe a homozygous ultra-rare REV3L variant (T2753R) identified with whole exome sequencing in a child without Moebius syndrome but with developmental delay, hypotrophy, and dysmorphic features who was born to healthy parents (heterozygous carriers of the variant). The variant affects the amino acid adjacent to functionally important KKRY motif. By introducing an equivalent mutation (S1192R) into the REV3 gene in yeasts, we showed that, whereas it retained residual function, it caused clear dysfunction of TLS in the nucleus and instability of mitochondrial genetic information. In particular, the mutation increased UV sensitivity measured by cell survival, decreased both the spontaneous (P < 0.005) and UV-induced (P < 0.0001) mutagenesis rates of nuclear DNA and increased the UV-induced mutagenesis rates of mitochondrial DNA (P < 0.0005). We propose that our proband is the first reported case of a REV3L associated disease different from Moebius syndrome both in terms of clinical manifestations and inheritance (autosomal recessive rather than dominant). KEY MESSAGES: First description of a human recessive disorder associated with a REV3L variant. A study in yeast showed that the variant affected the enzymatic function of the protein. In particular, it caused increased UV sensitivity and abnormal mutagenesis rates.

Carriership of the rs113883650/rs2287120 haplotype of the SLC7A5 (LAT1) gene increases the risk of obesity in infants with phenylketonuria.

PURPOSE: Phenylketonuria (PKU) can be effectively treated with the use of a low-phenylalanine diet. However, some patients become overweight despite proper dietary treatment. We hypothesized that this phenomenon could be explained by the presence of specific variants within the genes involved in phenylalanine transport or in the phenylalanine transamination/oxygenation pathway. METHODS: We selected a clinically homogenous group of 100 infants with PKU and assessed their growth patterns in the context of dietary phenylalanine tolerance. Next, within the sample, we performed exome sequencing and assessed a potential relationship between the observed phenotypical variability and the presence of structural variants in a priori selected genes of interest. RESULTS: We detected a highly significant association between overweight and carriership of the rs113883650/rs2287120 haplotype of the SLC7A5 (LAT1) gene, which encodes the main transmembrane transporter of large neutral amino acids and of thyroid hormones. CONCLUSIONS: Our findings suggest a pharmacogenetic effect of the relatively common rs113883650/rs2287120 haplotype of the SLC7A5 gene. This can have practical implications for patients with PKU, since treatment protocols need to be reassessed to better prevent overweight in the carriers of the above variant.

High Frequency of Fusion Gene Transcript Resulting From t(10;11)(p12;q23) Translocation in Pediatric Acute Myeloid Leukemia in Poland.

11q23/MLL rearrangements are frequently detected in pediatric acute myeloid leukemia. The analysis of their clinical significance is difficult because of the multitude of translocation fusion partners and their low frequency. The presence of t(10;11)(p12;q23) translocation was previously identified in pediatric acute myelogenous leukemia (AML). It is considered as the second most common translocation detected in pediatric 11q23/MLL-rearranged (present KMT2A) AML, after t(9;11)(p22;q23). The presence of the above translocation was previously identified as an unfavorable prognostic factor. Since June 2015, the Polish Pediatric Leukemia/Lymphoma Study Group has applied the therapeutic protocol requiring extensive diagnostics of genetic changes in pediatric AML. Until November 2019, molecular genetic studies were performed in 195 children with diagnosed AML to identify carriers of fusion gene transcripts for 28 most common chromosomal translocations in acute leukemia. The fusion gene transcript for translocation t(10;11)(p12;q23) involving MLL gene was detected with unexpectedly high frequency (8.9%) in our research. It was the highest frequency of all detected MLL rearrangements, as well as other detected fusion gene transcripts from chromosomal aberrations characteristic for AML. It seems that chromosomal aberration between chromosomes 10 and 11 can be relatively frequent in some populations. Paying attention to this fact and ensuring proper genetic diagnosis seem to be important for appropriate allocation of patients to risk groups of pediatric AML treatment protocols.

Polymorphisms of SLC19A1 80 G>A, MTHFR 677 C>T, and Tandem TS Repeats Influence Pharmacokinetics, Acute Liver Toxicity, and Vomiting in Children With Acute Lymphoblastic Leukemia Treated With High Doses of Methotrexate.

Introduction: High dose methotrexate (HD-Mtx) is highly effective and significantly improves overall acute lymphoblastic leukemia (ALL) patients survival. The pharmacodynamics of Mtx depends on the polymorphism of genes encoding proteins engaged in the folate metabolism pathway. The aim of the current study is to determine the relationship between variants of folate metabolism-related genes and the frequency of acute toxicities of HD-Mtx. Material and Methods: A group of 133 patients aged 1.5-18.1 years (median: 6.3) was treated in accordance with the ALL-IC-2002 and ALL-IC-2009 protocols. The following polymorphisms were determined: 80 G>A SLC19A1 (solute carrier family 19 member 1; rs1051266) with direct DNA sequencing, as well as 677 C>T MTHFR (methylenetetrahydrofolate reductase; rs1801133) and the tandem repeats of the TS (thymidylate synthase) with PCR technique. HD-Mtx organ toxicities were evaluated based on the laboratory tests results and the National Cancer Institute criteria. Results: In patients with genotypes AA for SLC19A1 and CC or CT for MTHFR Mtx steady state concentrations (Css) and AUCinf were distinctly higher. In patients with genotype 3R/3R for TS initial elimination rate constant was significantly higher (P = 0.003). Patients receiving Mtx at the dose of 5 g/m2 had lower clearance (4.35 vs. 8.92 L/h/m2) as compared to the ones receiving 2 g/m2 that indicates non-linear Mtx elimination at the higher dose. Liver impairment was the most frequently observed toxicity. The homozygous genotype was associated with a significantly higher incidence of hepatic toxicity for both the SLC19A1 (P = 0.037) and TS (P = 0.002). Logistic regression analysis indicated an increased risk of vomiting for the 2R/3R genotype of the TS gene (OR 3.20, 95% CI 1.33-7.68, P = 0.009) and for vomiting and hepatic toxicity for the 3R/3R genotype (vomiting: OR 3.39, 95% CI 1.12-10.23, P = 0.031; liver toxicity: OR 2.28, 95% CI 1.05-4.95, P = 0.038). None of the acute toxicities differed between the analyzed dosing groups. Conclusions: Determination of polymorphisms of SLC19A1, MTHFR, and TS genes might allow for a better prior selection of patients with higher risk of elevated Mtx levels. Our study is the first one to report the increased risk of hepatotoxicity and vomiting in patients with TS polymorphisms.

Case report of endoprosthesis -Y implantation in severe respiratory failure in the MPSII patient; comparison with literature data.

BACKGROUND: The tracheobronchomalacia is a life-threatening complication of mucopolysaccharidosis (MPS) without known effective, optimal treatment. The severe expiratory collapse of the trachea and bronchi is one of causes of the high rate of deaths in the course of airway impairment in MPSII patients. CASE PRESENTATION: Due to the adynamic tracheobronchomalacia despite of enzymatic treatment (ERT) in our MPSII patient, a life-saving tracheal bifurcated type-Y endoprosthesis (a self-expanding, metal stent for the prosthesis of tracheal and bronchial stenosis) was implanted. In the followed months, the breathing efficiency improved, but then gradual worsening, progression of bronchi occlusion at the stent border resulted in patient's death. CONCLUSION: The Y-stent implantation appears to be a short-term, life-saving solution without satisfactory long-term effects due to the progress of peripheral bronchomalacia and increased tissue proliferation and granulation, that arises during the illness' course.

Transcriptome analysis reveals dysregulation of genes involved in oxidative phosphorylation in a murine model of retinopathy of prematurity.

BACKGROUND: Retinal gene expression pattern is severely altered after exposition to hyperoxia in mice with oxygen-induced retinopathy (OIR), a common model of retinopathy of prematurity. Gene ontology and signaling pathway analyses may add new insights into a better understanding of the pathogenesis of this disease. METHODS: Seven-day-old C57BL/6J mice (n = 60) were exposed to 75% oxygen for 5 days and then recovered in room air. The controls (n = 60) were kept in the normoxic conditions. Retinas were harvested immediately following hyperoxia, during the phase of maximal neovascularization, and at the time of neovascularization regression. The retinal RNA samples were evaluated for gene expression using mouse gene expression microarrays. DAVID annotation tools were used for gene ontology and pathway analyses. RESULTS: The most significantly enriched signaling pathways during the neovascularization phase of OIR were: focal adhesion; ECM-receptor interaction; PI3K-Akt; oxidative phosphorylation; and Alzheimer's, Parkinson's and Huntington's disease signaling pathways. Genes involved in apoptosis, cell proliferation, cell differentiation, and immune responses were associated with neovascularization regression. CONCLUSIONS: Performed analyses revealed the possible involvement of various signaling pathways in OIR pathomechanism, mostly specific to the OIR phase. Dysregulation of genes involved in oxidative phosphorylation may have an impact on neovascularization development.

Short- and long-term impact of hyperoxia on the blood and retinal cells' transcriptome in a mouse model of oxygen-induced retinopathy.

BACKGROUND: We aimed to identify global blood and retinal gene expression patterns in murine oxygen-induced retinopathy (OIR), a common model of retinopathy of prematurity, which may allow better understanding of the pathogenesis of this severe ocular prematurity complication and identification of potential blood biomarkers. METHODS: A total of 120 C57BL/6J mice were randomly divided into an OIR group, in which 7-day-old pups were maintained in 75% oxygen for 5 days, or a control group. RNA was extracted from the whole-blood mononuclear cells and retinal cells on days 12, 17, and 28. Gene expression in the RNA samples was evaluated with mouse gene expression microarrays. RESULTS: There were 38, 1370 and 111 genes, the expression of which differed between the OIR and control retinas on days 12, 17, and 28, respectively. Gene expression in the blood mononuclear cells was significantly altered only on day 17. Deptor and Nol4 genes showed reduced expression both in the blood and retinal cells on day 17. CONCLUSION: There are sustained marked changes in the global pattern of gene expression in the OIR mice retinas. An altered expression of Deptor and Nol4 genes in the blood mononuclear cells requires further investigation as they may indicate retinal neovascularization.

Hypermethylation of NRG1 gene correlates with the presence of heart defects in Down's syndrome.

Congenital heart defects can decrease the quality of life and life expectancy in affected individuals, and constitute a major burden for the health care systems. Endocardial cushion defects are among the most prevalent heart malformations in the general population, and are extremely frequent (approximately a 100-fold higher prevalence) in children with Down syndrome. Several genes have been proposed to be involved in the pathogenesis of these malformations, but no common pathogenic DNA variants have been identified so far. Here, we focussed on constitutive, epigenetic alterations of function of selected genes, potentially important for endocardial cushion development. We used two types of microarrays, dedicated for assessment of gene promoter methylation and whole genome expression. First, we compared the gene promoter methylation profiles between two groups of Down syndrome patients, with and without heart defects of endocardial cushion-type. Then, to determine the functional role of the detected methylation alterations, we assessed the expression of the genes of interest. We detected significant hypermethylation of the NRG1 gene promoter region in children with heart defects. NRG1 is a key factor in maturation of endocardial cushions. Supplementary gene expression assessment revealed significantly decreased activity of the ERBB3, SHC3 and SHC4 genes in children with heart defects. The above three genes are closely related to the NRG1 gene and are crucial elements of the NRG/ErbB pathway. The results of this pilot study show that hypermethylation of the NRG1 gene promoter can reflect the functional genome alteration contributing to development of congenital heart defects of endocardial cushion-type.