Genetic and epigenetic methylation defects and implication of the ERMN gene in autism spectrum disorders.

Autism spectrum disorders (ASD) are highly heritable and genetically complex conditions. Although highly penetrant mutations in multiple genes have been identified, they account for the etiology of <1/3 of cases. There is also strong evidence for environmental contribution to ASD, which can be mediated by still poorly explored epigenetic modifications. We searched for methylation changes on blood DNA of 53 male ASD patients and 757 healthy controls using a methylomic array (450K Illumina), correlated the variants with transcriptional alterations in blood RNAseq data, and performed a case-control association study of the relevant findings in a larger cohort (394 cases and 500 controls). We found 700 differentially methylated CpGs, most of them hypomethylated in the ASD group (83.9%), with cis-acting expression changes at 7.6% of locations. Relevant findings included: (1) hypomethylation caused by rare genetic variants (meSNVs) at six loci (ERMN, USP24, METTL21C, PDE10A, STX16 and DBT) significantly associated with ASD (q-value <0.05); and (2) clustered epimutations associated to transcriptional changes in single-ASD patients (n=4). All meSNVs and clustered epimutations were inherited from unaffected parents. Resequencing of the top candidate genes also revealed a significant load of deleterious mutations affecting ERMN in ASD compared with controls. Our data indicate that inherited methylation alterations detectable in blood DNA, due to either genetic or epigenetic defects, can affect gene expression and contribute to ASD susceptibility most likely in an additive manner, and implicate ERMN as a novel ASD gene.

Influence of fetal glutathione S-transferase copy number variants on adverse reproductive outcomes.

A nested case-control association study was designed to investigate the influence of maternal and fetal copy number variants (CNVs) on reproductive outcomes. Genotypes of ten CNVs encompassing GST and CYP genes were assessed. Significant associations were only found for child CNV genotypes. In particular, the child GSTM1 insertion allele was associated with prematurity protection (odds ratio, 95% CI: 0.67, 0.51-0.89; P < 0.01), whereas the child GSTT2B insertion allele was associated with an increased risk of being small for gestational age (odds ratio, 95% CI: 1.33, 1.07-1.67; P = 0.01). The study highlights the role of the fetal genome in prenatal development and also the need to analyse CNVs in a systematic manner.

Water disinfection by-products and bladder cancer: is there a European specificity? A pooled and meta-analysis of European case-control studies.

Several epidemiological studies suggested an association between the risk of bladder cancer and the exposure to trihalomethanes (THMs), the main disinfection by-products (DBPs) of chlorinated water. A previous pooled analysis of case-control studies from North America and Europe estimated a summarized dose-response relation. For policy guidance of drinking water disinfection in Europe and because major differences exist in water disinfection practices and DBPs occurrence between both continents, specific risk estimates for bladder cancer in relation to DBPs exposure for European populations were needed. We conducted a pooled and a two-stage random-effect meta-analyses of three European case-control studies from France, Finland, and Spain (5467 individuals: 2381 cases and 3086 controls). Individual exposure to THMs was calculated combining information on residential history, estimates of the average total THMs (TTHM) level in tap water at the successive residences and personal water consumption. A significant odds-ratio was observed for men exposed to an average residential TTHM level > 50 µg/l (OR = 1.47 (1.05; 2.05)) when compared to men exposed to levels ≤ 5 µg/l. The linear trend of the exposure-risk association was significant (p = 0.01). Risks increased significantly for exposure levels above 25 µg/l and with more than 30 years of exposure to chlorinated water, but were mainly driven by the level rather than the duration of exposure. No significant association was found among women or with cumulative exposure through ingestion. There was no evidence of a differential exposure-response relation for TTHM and bladder cancer in Europe and North America. Consequently, a global exposure-risk relation based on 4351 cases and 7055 controls is now available.

COGENT (COlorectal cancer GENeTics): an international consortium to study the role of polymorphic variation on the risk of colorectal cancer.

It is now recognised that a part of the inherited risk of colorectal cancer (CRC) can be explained by the co-inheritance of low-penetrance genetic variants. The accumulated experience to date in identifying these variants has served to highlight difficulties in conducting statistically and methodologically rigorous studies and follow-up analyses. The COGENT (COlorectal cancer GENeTics) consortium includes 20 research groups in Europe, Australia, the Americas, China and Japan. The overarching goal of COGENT is to identify and characterise low-penetrance susceptibility variants for CRC through association-based analyses. In this study, we review the rationale for identifying low-penetrance variants for CRC and our proposed strategy for establishing COGENT.

Swimming pool attendance and risk of asthma and allergic symptoms in children.

Increased asthma risk has been associated with pool attendance in children but evidence is inconsistent and inconclusive. A survey was conducted of 3,223 9-12-yr-old children in Sabadell (Spain) to evaluate association between swimming pool attendance and prevalence of asthma and allergic conditions and symptoms. Parents completed a questionnaire on lifetime frequency of pool attendance and symptoms in the last 12 months (wheezing, asthma medication, rhinitis and allergic rhinitis), ever having asthma and eczema, and potential confounders. Indicators of indoor and outdoor swimming pool attendance early in life, cumulatively and currently were calculated. Swimming pool attendance before the age of 2 yrs was associated with slightly lower prevalence of current asthma (OR 0.79, 95% CI 0.43-1.46), rhinitis (OR 0.86, 95% CI 0.68-1.08) and allergic rhinitis symptoms (OR 0.72, 95% CI 0.54-0.96) compared to those who started attending swimming pools after 4 yrs of age. An increased prevalence of eczema was associated with duration of lifetime pool attendance (OR 1.71, 95%CI 1.38-2.12 for >5 yrs versus 0 yrs). Swimming pool attendance in Spanish children was associated with slightly less upper and lower respiratory tract symptoms and with more eczema. Longitudinal studies are required to confirm these findings and avoid potential reverse causation.

A case-control study of the relation between plasma selenium and asthma in European populations: a GAL2EN project.

BACKGROUND: There is evidence that selenium levels are relatively low in Europe and may be falling. Low levels of selenium or low activity of some of the enzymes dependent on selenium have been associated with asthma. METHODS: The GA(2)LEN network has organized a multicentre case-control study in Europe to assess the relation of plasma selenium to asthma. The network compared 569 cases in 14 European centres with a diagnosis of asthma and reporting asthma symptoms in the last 12 months with 576 controls from the same centres with no diagnosis of asthma and no asthmatic symptoms in the last 12 months. RESULTS: All cases and controls were selected from the same population defined by age and place of residence. Mean plasma selenium concentrations among the controls ranged from 116.3 microg/l in Palermo to 67.7 microg/l in Vienna and 56.1 microg/l among the children in Oslo. Random effects meta-analysis of the results from the centres showed no overall association between asthma and plasma selenium [odds ratio (OR)/10 microg/l increase in plasma selenium: 1.04; 95% confidence interval (CI): 0.89-1.21] though there was a significantly protective effect in Lodz (OR: 0.48; 95% CI: 0.29-0.78) and a marginally significant adverse effect in Amsterdam (OR: 1.68; 95% CI: 0.98-2.90) and Ghent (OR: 1.35; 95% CI: 1.03-1.77). CONCLUSION: This study does not support a role for selenium in protection against asthma, but effect modification and confounding cannot be ruled out.

The relation between paracetamol use and asthma: a GA2LEN European case-control study.

Studies from the UK and USA suggest that frequent use of paracetamol (acetaminophen) may increase the risk of asthma, but data across Europe are lacking. As part of a multicentric case-control study organised by the Global Allergy and Asthma European Network (GA(2)LEN), it was examined whether or not frequent paracetamol use is associated with adult asthma across Europe. The network compared 521 cases with a diagnosis of asthma and reporting of asthma symptoms within the last 12 months with 507 controls with no diagnosis of asthma and no asthmatic symptoms within the last 12 months across 12 European centres. All cases and controls were selected from the same population, defined by age (20-45 yrs) and place of residence. In a random effects meta-analysis, weekly use of paracetamol, compared with less frequent use, was strongly positively associated with asthma after controlling for confounders. There was no evidence for heterogeneity across centres. No association was seen between use of other analgesics and asthma. These data add to the increasing and consistent epidemiological evidence implicating frequent paracetamol use in asthma in diverse populations.

Assessment of lifetime exposure to trihalomethanes through different routes.

OBJECTIVES: To evaluate lifetime exposure to trihalomethanes (THM) through ingestion, inhalation, and dermal absorption in a hospital based case-control study of bladder cancer conducted between 1998 and 2001 in five areas of Spain. The study base was comprised of subjects living in the catchment areas of the participating hospitals. METHODS: Individual information on water related habits was obtained from personal interviews of 1219 cases and 1271 controls: residential and occupational history, drinking water source at each residence and job, amount of water consumption, frequency and duration of showering, bathing, and swimming pool attendance. THM levels, water source history, and year when chlorination started in study areas were ascertained through measurements in drinking water samples and questionnaires to water companies and local authorities. Estimates of THM levels covered 79% of the subjects' person-years of exposure. RESULTS: Current and historical average THM levels in water were correlated. Control subjects reported that drinking water source in the last residence was municipal for 63%, bottled for 22%, private well for 2%, and other sources for 13%. For the time window between age 15 and the time of interview, average residential THM level was 32.2 mug/l. THM exposure through ingestion was 23.7 mug/day on average, and was correlated with the ingestion THM level in the workplace. Overall, 79% usually took showers, 16% usually took baths, and 13% had ever attended a swimming pool. Between 21% and 45% of controls unexposed to THM through ingestion were evaluated as moderately or highly exposed through showering or bathing, and 5-10% were exposed through swimming in pools. CONCLUSION: The importance of evaluating different routes is underscored by findings from experimental studies showing substantial differences in THM uptake and internal distribution by route.

Atrazine in municipal drinking water and risk of low birth weight, preterm delivery, and small-for-gestational-age status.

BACKGROUND: Atrazine is a herbicide used extensively worldwide. Bioassays have shown that it is embryotoxic and embryolethal. Evidence of adverse reproductive outcomes from exposure in the general population is sparse. AIMS: To evaluate the association between atrazine levels in municipal drinking water and the following adverse reproductive outcomes: increased risk of preterm delivery, low birth weight (LBW), and small-for-gestational-age (SGA) status. METHODS: A total of 3510 births that took place from 1 October 1997, to 30 September 1998 were analysed. Atrazine measurements were available for 2661 samples from water treatment plants over the past decade. A seasonal pattern was identified, with atrazine peaking from May to September. The geometric mean of the atrazine level for this period was calculated for each water distribution unit and merged with the individual data by municipality of residence. RESULTS: Atrazine levels in water were not associated with an increased risk of LBW or SGA status and were slightly associated with prematurity. There was an increased risk of SGA status in cases in which the third trimester overlapped in whole or in part with the May-September period, compared with those in which the third trimester occurred totally from October to April (OR = 1.37, 95% CI 1.04 to 1.81). If the entire third trimester took place from May to September, the OR was 1.54 (95% CI 1.11 to 2.13). CONCLUSIONS: Low levels of atrazine, a narrow exposure range, and limitations in the exposure assessment partly explain the lack of associations with atrazine. Findings point to the third trimester of pregnancy as the potential vulnerable period for an increased risk of SGA birth. Exposures other than atrazine and also seasonal factors may explain the increased risk.

Meta-analysis of studies on individual consumption of chlorinated drinking water and bladder cancer.

STUDY OBJECTIVE: To evaluate whether consumption of chlorinated drinking water is associated with bladder cancer. DESIGN: A bibliographic search was conducted and the authors selected studies evaluating individual consumption of chlorinated drinking water and bladder cancer. The authors extracted from each study risk estimates for intermediate and long term (>40 years) consumption of chlorinated water, stratified by sex when possible, and performed meta-analysis for the two exposure levels. A meta-analysis was also performed of the dose-response regression slopes. SETTING: Populations in Europe and North America. PARTICIPANTS: Those included in six case-control studies (6084 incident bladder cancer cases, 10,816 controls) and two cohort studies (124 incident bladder cancer cases) fulfilling the inclusion criteria. MAIN RESULTS: Ever consumption of chlorinated drinking water was associated with an increased risk of bladder cancer in men (combined OR=1.4, 95%CI 1.1 to 1.9) and women (combined OR=1.2, 95%CI 0.7 to 1.8). The combined OR for mid-term exposure in both genders was 1.1 (95% CI 1.0 to 1.2) and for long term exposure was 1.4 (95%CI 1.2 to 1.7). The combined estimate of the slope for a linear increase in risk was 1.13 (95% CI 1.08 to 1.20) for 20 years and 1.27 (95% CI 1.15 to 1.43) for 40 years of exposure in both sexes. CONCLUSIONS: This meta-analysis of the best available epidemiological evidence indicates that long term consumption of chlorinated drinking water is associated with bladder cancer, particularly in men. The observed relative risk is only moderately high, but the population attributable risk could be important as the vast majority of the population of industrialised countries is potentially exposed to chlorination byproducts for long time periods.

Haloacetic acids and trihalomethanes in finished drinking waters from heterogeneous sources.

Trihalomethanes (THM) and haloacetic acids (HAA) are the most frequent chlorination by-products (CBP) in finished drinking waters. Traditionally, THM have been used as surrogates for CBP although the quantitative association between THM and other CBP is not well established. This problem is addressed in the present study from the analysis of THM and HAA in drinking water samples from four Spanish regions, representing areas with very different CBP composition, e.g. between 86 and 8.0 microg/l of THM and 50-3.0 microg/l of HAA. The resulting dataset exhibit a statistically significant correlation between total THM and HAA (Pearson's correlation coefficient, r(p)=0.815,p<0.0005). Furthermore, specific HAA are highly correlated with specific THM or their combinations. Accordingly, multivariate linear regression analysis of the concentrations observed show that the levels in total and specific HAA can be predicted from the THM content. These results are relevant for epidemiological studies on health effects from CBP exposure since they usually involve comparison of populations consuming waters of very distinct quality.

[Chlorination of drinking water in Spain and bladder cancer]. / Cloración del agua potable en España y cáncer de vejiga.

OBJECTIVES: Drinking water chlorination generates trihalomethanes and other by-products with mutagenic and carcinogenic properties in animal experiments. Epidemiological studies have associated trihalomethanes to an increased risk of bladder cancer. We evaluate trihalomethane levels in four Spanish areas and calculate the bladder cancer risk attributable to this exposure. METHODS: Trihalomethanes have been analysed in 111 drinking water samples from four Spanish areas using gas chromatography. Water utilities were contacted and information on drinking water consumption in Spain has been collected. We reviewed the epidemiological studies that assess the association between bladder cancer risk and exposure to chlorination by-products. Attributable risk was calculated on the basis of these levels, mortality data per area and risk estimates obtained from the literature. RESULTS: Mediterranean areas present the highest levels of trihalomethanes with 81, 80, 61 and 52 µg/l in Sabadell, Alicante, Barcelona and Manresa respectively. Lower levels are found in Tenerife and Asturias with 7 and 20 µg/l respectively. The bladder cancer attributable risk in high trihalomethane exposure areas may be, on average, around 20%. CONCLUSIONS: The trihalomethane levels found are high compared to those of other European Union countries. In the high exposure areas, drinking water chlorination may generate a considerable number of bladder cancer cases. These estimations have to be carefully interpreted and verified with more extensive studies.

[Treatment of bronchial asthma in winter using controlled-release salbutamol]. / Tratamiento del asma bronquial en el periodo invernal con salbutamol de liberación controlada.

This paper presents results about comparative study in winter season, in a statistics design AB and BA on 20 patients that were treated with salbutamol (Group B) and with salbutamol of controlled liberation (Group B) at random. Results showed that patients of Group B had improvement in symptomatology and had less exacerbations than those patients of group A with statistical significance. It was concluded that salbutamol tablets of controlled liberation is a therapeutic method adequate to control chronic phase of asthmatic patients in winter season.