Laktaasinpuutosten molekyyligenetiikka

Congenital lactase deficiency (CLD) (MIM 223000) is a rare autosomal recessive gastrointestinal disorder characterized by watery diarrhea in infants fed with breast milk or other lactose-containing formulas. The CLD locus was previously assigned by linkage and linkage disequilibrium analyses on 2q21 in 19 Finnish families. In this study, the molecular background of this disorder is reported. The CLD locus was refined in 32 CLD patients in 24 families by using microsatellite and single nucleotide polymorphism (SNP) haplotypes. Mutation analyses were performed by direct sequencing. We identified 5 distinct mutations in the lactase (LCT) gene, encoding the enzyme that hydrolyzes lactose in the intestinal lumen. These findings facilitate genetic testing of CLD in clinical practice and enable genetic counseling. The present data also provide the basis for detailed characterization of the molecular pathogenesis of this disorder. Adult-type hypolactasia (MIM 223100) (lactase non-persistence, lactose intolerance) is an autosomal recessive gastrointestinal condition that is a result of a decline in the activity of lactase in the intestinal lumen after weaning. Adult-type hypolactasia is considered to be a normal phenomenon among mammals and symptoms are remarkably milder than experienced in CLD. Recently, a variant C/T-13910 was shown to associate with the adult-type hypolactasia trait, locating 13.9 kb upstream of the LCT gene. In this study, the functional significance of the C/T-13910 variant was determined by studying the LCT mRNA levels in intestinal biopsy samples in children and adults with different genotypes. RT-PCR followed by solid-phase minisequencing was applied to determine the relative expression levels of the LCT alleles using an informative SNP located in exon 1. In children, the C-13910 allele was observed to be downregulated after five years of age in parallel with lactase enzyme activity. The expression of the LCT mRNA in the intestinal mucosa in individuals with the T-13910 A-22018 alleles was 11.5 times higher than that found in individuals with the C-13910, G-22018 alleles. These findings suggest that the C/T-13910 associated with adult-type hypolactasia is associated with the transcriptional regulation of the LCT gene. The presence of the T-13910 A-22018 allele also showed significant elevation lactase activity. Galactose, the hydrolysing product of the milk sugar lactose, has been hypothesized to be poisonous to ovarian epithelial cells. Hence, consumption of dairy products and lactase persistence has been proposed to be a risk factor for ovarian carcinoma. To investigate whether lactase persistence is related to the risk of ovarian carcinoma the C/T-13910 genotype was determined in a cohort of 782 women with ovarian carcinoma 1331 individuals serving as controls. Lactase persistence did not associate significantly with the risk for ovarian carcinoma in the Finnish, in the Polish or in the Swedish populations. The findings do not support the hypothesis that lactase persistence increases the risk for ovarian carcinoma.Synnynnäinen laktaasin puutos (congenital lactase deficiency, CLD [MIM 223000]) on vakava peittyvästi periytyvä suolistosairaus. Potilailla on tyypillistä runsas vetinen ripuli, joka ilmenee maitoruokinnan alettua. Ripuli johtaa ravintoaineiden imeytymishäiriöön ja kasvun hidastumiseen. Potilaiden laktaasiaktiivisuus on havaittu ohutsuolessa hyvin alhaiseksi. Vaikea ripuli johtuu nimenomaan hydrolysoimattoman laktoosin kertymisestä suolistoon aiheuttaen osmoosin, vaikean kuivumistilan, asidoosin ja painon menetyksen syntymäpainon alapuolelle. Laktoositon ruokavalio poistaa oireet ja palauttaa kehityksen normaaliksi. CLD-vauvoja syntyy Suomessa yksi vuodessa (1:60000). Se kuuluu yhdessä 36 muun harvinaisen Suomessa esiintyvän sairauden kanssa ns. suomalaiseen tautiperintöön. Tutkimuksen tarkoituksena oli tunnistaa CLD:lle altistavat geneettiset tekijät geenien kartoitus- ja sekvensointimenetelmien avulla. Tutkimuksessa analysoitiin 32 CLD-potilasta 24 eri perheestä. Löysimme viisi CLD:lle altistavaa mutaatiota laktaasigeenistä (LCT), joista Y1390X-mutaation havaittiin olevan yleisin ns. Finmajor-mutaatio. Löydökset mahdollistavat sairauden perinnöllisen testauksen ja neuvonnan. Lapsuuden jälkeen tai nuorella aikuisiällä havaittu primääri maitosokerin imeytymishäiriö (MIM 223100) (tunnettu myös laktoosi-intoleranssina) on yleinen laktaasin aktiivisuuden alenemisesta johtuva ilmiö. Laktaasiaktiivisuus alenee suolistossa 5-10% lapsuudesta havaitusta ja laktoosi ruokavaliossa aiheuttaa suolistoperäisiä oireita. Laktaasin puutos on nisäkkäille luonnollinen ilmiö, näin lapsi vierotetaan rinnasta käyttämään kiinteätä ravintoa. Kuitenkin joillain ihmisillä korkea laktaasiaktivisuus säilyy koko elinajan. Kyseiseen ilmiasuun on havaittu liittyvän yhden emäksen muutos C→T-13910 noin 14 kiloemästä laktaasigeenistä ylävirtaan. T-13910-muutoksen perineet henkilöt säilyttävät laktaasiaktiivisuuden ja kyvyn pilkkoa laktoosia. Tämän tutkimuksen tarkoituksena oli määrittää C/T-13910 emäsmuutoksen vaikutus laktaasigeenin ilmentymiseen lähetti-RNA tasolla lapsilla ja aikuisilla. Laktaasigeenin ilmentymistä tutkittiin geenispesifisellä minisekvensointimenetelmällä pohjukaissuolesta otetuista näytteistä. Havaitsimme, että laktaasia säädellään transkriptiotasolla, C-13910-muutos sallii laktaasigeenin lähetti-RNA:n laskun. Ilmiö oli havaittavissa lapsilla viiden ikävuoden jälkeen. Aikuisilla T-13910-emäsmuutos vastasi 92% havaitusta laktaasigeenin lähetti-RNA:n ilmentymisestä, joka näkyi myös korkeana laktaasiaktiivisuutena. Galaktoosi on glukoosin ohella laktoosin hajoamistuote. Galaktoosin on havaittu eläinkokeissa olevan myrkyllinen munasarjojen epiteelisoluille ja sen on epäilty aiheuttavan munasarjasyöpää. Tästä syystä korkean laktaasiaktiivisuuden ja maitotuotteiden runsaan nauttimisen on oletettu nostavan munasarjasyövän riskiä. Tässä tutkimuksessa määritettiin 782 suomalaisen, puolalaisen ja ruotsalaisen munasarjasyöpäpotilaan ja 1331 verrokkinäytteen C/T-13910-genotyyppi tutkiaksemme onko korkealla laktaasiaktiivisuudella yhteyttä syövän syntyyn. Genotyypillä ei havaittu olevan vaikutusta syöpäriskiin tutkituissa väestöryhmissä. Jatkotutkimuksella pyritään selvittämään maitotuotteiden kulutuksen merkitystä munasarjasyöpään eri C/T-13910 genotyypeillä

Genome-Wide Association Studies of Asthma in Population-Based Cohorts Confirm Known and Suggested Loci and Identify an Additional Association near HLA

Rationale Asthma has substantial morbidity and mortality and a strong genetic component, but identification of genetic risk factors is limited by availability of suitable studies. Objectives To test if population-based cohorts with self-reported physician-diagnosed asthma and genome-wide association (GWA) data could be used to validate known associations with asthma and identify novel associations. Methods The APCAT (Analysis in Population-based Cohorts of Asthma Traits) consortium consists of 1,716 individuals with asthma and 16,888 healthy controls from six European-descent population-based cohorts. We examined associations in APCAT of thirteen variants previously reported as genome-wide significant (P<5x10−8) and three variants reported as suggestive (P<5×10−7). We also searched for novel associations in APCAT (Stage 1) and followed-up the most promising variants in 4,035 asthmatics and 11,251 healthy controls (Stage 2). Finally, we conducted the first genome-wide screen for interactions with smoking or hay fever. Main Results We observed association in the same direction for all thirteen previously reported variants and nominally replicated ten of them. One variant that was previously suggestive, rs11071559 in RORA, now reaches genome-wide significance when combined with our data (P = 2.4×10−9). We also identified two genome-wide significant associations: rs13408661 near IL1RL1/IL18R1 (PStage1+Stage2 = 1.1x10−9), which is correlated with a variant recently shown to be associated with asthma (rs3771180), and rs9268516 in the HLA region (PStage1+Stage2 = 1.1x10−8), which appears to be independent of previously reported associations in this locus. Finally, we found no strong evidence for gene-environment interactions with smoking or hay fever status. Conclusions Population-based cohorts with simple asthma phenotypes represent a valuable and largely untapped resource for genetic studies of asthma.Public Library of Science open acces

Identification of healthspan-promoting genes in Caenorhabditis elegans based on a human GWAS study

To find drivers of healthy ageing, a genome-wide association study (GWAS) was performed in healthy and unhealthy older individuals. Healthy individuals were defined as free from cardiovascular disease, stroke, heart failure, major adverse cardiovascular event, diabetes, dementia, cancer, chronic obstructive pulmonary disease (COPD), asthma, rheumatism, Crohn’s disease, malabsorption or kidney disease. Six single nucleotide polymorphisms (SNPs) with unknown function associated with ten human genes were identified as candidate healthspan markers. Thirteen homologous or closely related genes were selected in the model organism C. elegans for evaluating healthspan after targeted RNAi-mediated knockdown using pathogen resistance, muscle integrity, chemotaxis index and the activity of known longevity and stress response pathways as healthspan reporters. In addition, lifespan was monitored in the RNAi-treated nematodes. RNAi knockdown of yap-1, wwp-1, paxt-1 and several acdh genes resulted in heterogeneous phenotypes regarding muscle integrity, pathogen resistance, chemotactic behaviour, and lifespan. Based on these observations, we hypothesize that their human homologues WWC2, CDKN2AIP and ACADS may play a role in health maintenance in the elderly

Differential and shared genetic effects on kidney function between diabetic and non-diabetic individuals

Reduced glomerular filtration rate (GFR) can progress to kidney failure. Risk factors include genetics and diabetes mellitus (DM), but little is known about their interaction. We conducted genome-wide association meta-analyses for estimated GFR based on serum creatinine (eGFR), separately for individuals with or without DM (nDM = 178,691, nnoDM = 1,296,113). Our genome-wide searches identified (i) seven eGFR loci with significant DM/noDM-difference, (ii) four additional novel loci with suggestive difference and (iii) 28 further novel loci (including CUBN) by allowing for potential difference. GWAS on eGFR among DM individuals identified 2 known and 27 potentially responsible loci for diabetic kidney disease. Gene prioritization highlighted 18 genes that may inform reno-protective drug development. We highlight the existence of DM-only and noDM-only effects, which can inform about the target group, if respective genes are advanced as drug targets. Largely shared effects suggest that most drug interventions to alter eGFR should be effective in DM and noDM

GABA(B) receptor positive allosteric modulators with different efficacies affect neuroadaptation to and self-administration of alcohol and cocaine

Drugs of abuse induce widespread synaptic adaptations in the mesolimbic dopamine (DA) neurons. Such drug-induced neuroadaptations may constitute an initial cellular mechanism eventually leading to compulsive drug-seeking behavior. To evaluate the impact of GABA(B) receptors on addiction-related persistent neuroplasticity, we tested the ability of orthosteric agonist baclofen and two positive allosteric modulators (PAMs) of GABA(B) receptors to suppress neuroadaptations in the ventral tegmental area (VTA) and reward-related behaviors induced by ethanol and cocaine. A novel compound (S)-1-(5-fluoro-2,3-dihydro-1H-inden-2-yl)-4-methyl-6,7,8,9-tetrahydro-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one (ORM-27669) was found to be a GABA(B) PAM of low efficacy as agonist, whereas the reference compound (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF) had a different allosteric profile being a more potent PAM in the calcium-based assay and an agonist, coupled with potent PAM activity, in the [S-35] GTP gamma S binding assay in rat and human recombinant receptors. Using autoradiography, the high-efficacy rac-BHFF and the low-efficacy ORM-27669 potentiated the effects of baclofen on [S-35] GTP gamma S binding with identical brain regional distribution. Treatment of mice with baclofen, rac-BHFF, or ORM-27669 failed to induce glutamate receptor neuroplasticity in the VTA DA neurons. Pretreatment with rac-BHFF at non-sedative doses effectively reversed both ethanol- and cocaine-induced plasticity and attenuated cocaine i.v. self-administration and ethanol drinking. Pretreatment with ORM-27669 only reversed ethanol-induced neuroplasticity and attenuated ethanol drinking but had no effects on cocaine-induced neuroplasticity or self-administration. These findings encourage further investigation of GABA(B) receptor PAMs with different efficacies in addiction models to develop novel treatment strategies for drug addiction.Peer reviewe

Influence of the Human Lipidome on Epicardial Fat Volume in Mexican American Individuals

Introduction: Cardiovascular disease (CVD) is the leading cause of mortality worldwide and is the leading cause of death in the US. Lipid dysregulation is a well-known precursor to metabolic diseases, including CVD. There is a growing body of literature that suggests MRI-derived epicardial fat volume, or epicardial adipose tissue (EAT) volume, is linked to the development of coronary artery disease. Interestingly, epicardial fat is also actively involved in lipid and energy homeostasis, with epicardial adipose tissue having a greater capacity for release and uptake of free fatty acids. However, there is a scarcity of knowledge on the influence of plasma lipids on EAT volume. Aim: The focus of this study is on the identification of novel lipidomic species associated with CMRI-derived measures of epicardial fat in Mexican American individuals. Methods: We performed lipidomic profiling on 200 Mexican American individuals. High-throughput mass spectrometry enabled rapid capture of precise lipidomic profiles, providing measures of 799 unique species from circulating plasma samples. Because of our extended pedigree design, we utilized a standard quantitative genetic linear mixed model analysis to determine whether lipids were correlated with EAT by formally testing for association between each lipid species and the CMRI epicardial fat phenotype. Results: After correction for multiple testing using the FDR approach, we identified 135 lipid species showing significant association with epicardial fat. Of those, 131 lipid species were positively correlated with EAT, where increased circulating lipid levels were correlated with increased epicardial fat. Interestingly, the top 10 lipid species associated with an increased epicardial fat volume were from the deoxyceramide (Cer(m)) and triacylglycerol (TG) families. Deoxyceramides are atypical and neurotoxic sphingolipids. Triacylglycerols are an abundant lipid class and comprise the bulk of storage fat in tissues. Pathologically elevated TG and Cer(m) levels are related to CVD risk and, in our study, to EAT volume. Conclusion: Our results indicate that specific lipid abnormalities such as enriched saturated triacylglycerols and the presence of toxic ceramides Cer(m) in plasma of our individuals could precede CVD with increased EAT volume

Differential and shared genetic effects on kidney function between diabetic and non-diabetic individuals

A large-scale GWAS provides insight on diabetes-dependent genetic effects on the glomerular filtration rate, a common metric to monitor kidney health in disease. Reduced glomerular filtration rate (GFR) can progress to kidney failure. Risk factors include genetics and diabetes mellitus (DM), but little is known about their interaction. We conducted genome-wide association meta-analyses for estimated GFR based on serum creatinine (eGFR), separately for individuals with or without DM (n(DM) = 178,691, n(noDM) = 1,296,113). Our genome-wide searches identified (i) seven eGFR loci with significant DM/noDM-difference, (ii) four additional novel loci with suggestive difference and (iii) 28 further novel loci (including CUBN) by allowing for potential difference. GWAS on eGFR among DM individuals identified 2 known and 27 potentially responsible loci for diabetic kidney disease. Gene prioritization highlighted 18 genes that may inform reno-protective drug development. We highlight the existence of DM-only and noDM-only effects, which can inform about the target group, if respective genes are advanced as drug targets. Largely shared effects suggest that most drug interventions to alter eGFR should be effective in DM and noDM.Peer reviewe

Genetic Variants in SGLT1, Glucose Tolerance, and Cardiometabolic Risk

BACKGROUND Loss-of-function mutations in the SGLT1 (sodium/glucose co-transporter-1) gene result in a rare glucose/galactose malabsorption disorder and neonatal death if untreated. In the general population, variants related to intestinal glucose absorption remain uncharacterized. OBJECTIVES The goat of this study was to identify functional SGLT1 gene variants and characterize their clinical consequences. METHODS Whole exome sequencing was performed in the ARIC (Atherosclerosis Risk in Communities) study participants enrolled from 4 U.S. communities. The association of functional, nonsynonymous substitutions in SGLT1 with 2-h oral glucose tolerance test results was determined. Variants related to impaired glucose tolerance were studied, and Mendelian randomization analysis of cardiometabotic outcomes was performed. RESULTS Among 5,687 European-American subjects (mean age 54 +/- 6 years; 47% mate), those who carried a haplotype of 3 missense mutations (frequency of 6.7%)-Asn51Ser, Ala411Thr, and His615Gln-had lower 2-h glucose and odds of impaired glucose tolerance than noncarriers (beta-coefficient: -8.0; 95% confidence interval [CI]: -12.7 to -3.3; OR: 0.71; 95% CI: 0.59 to 0.86, respectively). The association of the haplotype with oral glucose tolerance test results was consistent in a replication sample of 2,791 African-American subjects (beta = -16.3; 95% CI: -36.6 to 4.1; OR: 0.39; 95% CI: 0.17 to 0.91) and an external European-Finnish population sample of 6,784 subjects (beta = -3.2; 95% CI: -6.4 to 0.02; OR: 0.81; 95% CI: 0.68 to 0.98). Using a Mendelian randomization approach in the index cohort, the estimated 25-year effect of a reduction of 20 mg/dl in 2-h glucose via SGLT1 inhibition would be reduced prevalent obesity (OR: 0.43; 95% CI: 0.23 to 0.63), incident diabetes (hazard ratio [HR]: 0.58; 95% CI: 0.35 to 0.81), heart failure (HR: 0.53; 95% CI: 0.24 to 0.83), and death (HR: 0.66; 95% CI: 0.42 to 0.90). CONCLUSIONS Functionally damaging missense variants in SGLT1 protect from diet-induced hyperglycemia in multiple populations. Reduced intestinal glucose uptake may protect from long-term cardiometabolic outcomes, providing support for therapies that target SGLT1 function to prevent and treat metabolic conditions. (C) 2018 Published by Elsevier on behalf of the American College of Cardiology Foundation.Peer reviewe

Quantification and valuation of ecosystem services to optimize sustainable re-use for low-productive drained peatlands

LIFEPeatLandUse (LIFE12 ENV/FI/000150) 2013 – 2018, LAYMAN’S REPORT201

Genetic Variants of TSLP and Asthma in an Admixed Urban Population

Peer reviewe