[Show abstract][Hide abstract] ABSTRACT: CFTR mutations enhance susceptibility for idiopathic chronic pancreatitis (ICP) and congenital bilateral absence of the vas deferens (CBAVD); however, it is unknown why CFTR heterozygotes are at increased disease risk. We recently showed that common CFTR variants are associated with aberrantly spliced transcripts. Here, we genotyped for common CFTR variants and tested for associations in two ICP (ICP-A: 126 patients, 319 controls; ICP-B: 666 patients, 1,181 controls) and a CBAVD population (305 patients, 319 controls). Haplotype H10 (TG11-T7-470V) conferred protection (ICP-A: OR 0.19, P<0.0001; ICP-B: OR 0.78, P = 0.06; CBAVD OR 0.08, P<0.001), whereas haplotype H3 (TG10-T7-470M) increased disease risk (ICP-A: OR 8.34, P = 0.003; ICP-B: OR 1.88, P = 0.007; CBAVD: OR 5.67, P = 0.01). The risk of heterozygous CFTR mutations carriers for ICP (OR 2.44, P<0.001) and CBAVD (OR 14.73, P<0.001) was fully abrogated by the H10/H10 genotype. Similarly, ICP risk of heterozygous p.Asn34Ser SPINK1 mutation carriers (OR 10.34, P<0.001) was compensated by H10/H10. Thus, common CFTR haplotypes modulate ICP and CBAVD susceptibility alone and in heterozygous CFTR and p.Asn34Ser mutation carriers. Determination of these haplotypes helps to stratify carriers into high- and low-risk subjects, providing helpful information for genetic counseling.
Human Mutation 04/2011; 32(8):912-20. · 5.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In a genome-wide association study, a common variant on chromosome 11q13.5 (rs7927894[T]) has been identified as a susceptibility locus for eczema. We aimed to analyze the effect of this risk variant on asthma and hay fever and to determine its impact on the general population level in over 9300 individuals of the prospectively evaluated Avon Longitudinal Study of Parents and Children birth cohort. We demonstrate an association of rs7927894[T] with atopic asthma and with hay fever. The largest effect sizes were found in patients with the combined phenotype atopic asthma plus eczema [odds ratio (OR) = 1.50; 95% confidence interval (CI) 1.20-1.88; P = 3.7 × 10(-4)] and hay fever plus eczema (OR = 1.37; 95% CI 1.15-1.62; P = 3.8 × 10(-4)). We replicated the effects of rs7927894[T] on eczema-associated asthma and hay fever independently in the German GENUFAD (GEnetic studies in NUclear Families with Atopic Dermatitis) study and show that they are significantly larger than the effect observed in eczema. The estimated population attributable risk fractions for eczema, eczema-associated atopic asthma or hay fever were 9.3, 24.9 and 23.5%, respectively. Finally in eczema, we found a synergistic interaction of rs7927894[T] with filaggrin gene (FLG) mutations, which are a major cause of epidermal barrier dysfunction, and replicated the interaction in the German Multicenter Allergy Study birth cohort. The synergistic effect of rs7927894[T] and FLG mutations on eczema risk as well as the association of both variants with eczema-associated atopic asthma and hay fever point to an involvement of rs7927894[T] in a functional pathway that is linked to the barrier defect.
Human Molecular Genetics 03/2011; 20(12):2443-9. · 7.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Patients infected with human immunodeficiency virus type 1 (HIV-1) are considered to be at increased risk for 2009 H1N1 influenza-related complications. We performed an observational study after an outbreak of 2009 H1N1 influenza virus infection among a group of 15 HIV-1-infected school-aged children in Germany in October 2009. Clinical course, kinetics of viral shedding, and antibody response among children with CD4 cell counts >350 cells/μL and 2009 H1N1 influenza virus coinfection did not appear to differ from that among healthy children. Oseltamivir shortened the duration of viral shedding.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND:
Susceptibility to asthma is influenced by genes and environment; implicated genes may indicate pathways for therapeutic intervention. Genetic risk factors may be useful in identifying subtypes of asthma and determining whether intermediate phenotypes, such as elevation of the total serum IgE level, are causally linked to disease.
We carried out a genomewide association study by genotyping 10,365 persons with physician-diagnosed asthma and 16,110 unaffected persons, all of whom were matched for ancestry. We used random-effects pooled analysis to test for association in the overall study population and in subgroups of subjects with childhood-onset asthma (defined as asthma developing before 16 years of age), later-onset asthma, severe asthma, and occupational asthma.
We observed associations of genomewide significance between asthma and the following single-nucleotide polymorphisms: rs3771166 on chromosome 2, implicating IL1RL1/IL18R1 (P=3×10(−9)); rs9273349 on chromosome 6, implicating HLA-DQ (P=7×10(−14)); rs1342326 on chromosome 9, flanking IL33 (P=9×10(−10)); rs744910 on chromosome 15 in SMAD3 (P=4×10(−9)); and rs2284033 on chromosome 22 in IL2RB (P=1.1×10(−8)). Association with the ORMDL3/GSDMB locus on chromosome 17q21 was specific to childhood-onset disease (rs2305480, P=6×10(−23)). Only HLA-DR showed a significant genomewide association with the total serum IgE concentration, and loci strongly associated with IgE levels were not associated with asthma.
Asthma is genetically heterogeneous. A few common alleles are associated with disease risk at all ages. Implicated genes suggest a role for communication of epithelial damage to the adaptive immune system and activation of airway inflammation. Variants at the ORMDL3/GSDMB locus are associated only with childhood-onset disease. Elevation of total serum IgE levels has a minor role in the development of asthma. (Funded by the European Commission and others.)
New England Journal of Medicine 09/2010; 363(13):1211-1221. · 54.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A sustained imbalance of pancreatic proteases and their inhibitors seems to be important for the development of chronic pancreatitis (CP). Mesotrypsin (PRSS3) can degrade intrapancreatic trypsin inhibitors that protect against CP. Genetic variants that cause higher mesotrypsin activity might increase the risk for CP.
We analyzed all 5 exons and the adjacent non-coding sequences of PRSS3 by direct sequencing of 313 CP patients and 327 controls. Additionally, exon 4 was investigated in 855 patients and 1,294 controls and a c.454+191G>A variant in 855 patients and 1,467 controls. The c.499A>G (p.T167A) variant was analyzed functionally using transiently transfected HEK 293T cells.
In the exonic regions, the previously described common c.94_96delGAG (p.E32del) variant and a novel p.T167A non-synonymous alteration were identified. Extended analysis of the p.T167A variant revealed no association to CP and in functional assays p.T167A showed normal secretion and activity. Variants of the intronic regions, including the extensively analyzed c.454+191G>A alteration, were not associated with the disease. Haplotype reconstruction using variants with a minor allele frequency of >1% revealed no CP-associated haplotype.
Although the trypsin inhibitor-degrading activity qualified PRSS3 as a candidate for a novel CP susceptibility gene, we found no association between a specific variant or haplotype and CP in our cohort with a high suspicion of genetically determined disease.
[Show abstract][Hide abstract] ABSTRACT: Premature activation of pancreatic digestive enzymes is considered as a major factor in the pathogenesis of pancreatitis. Genetic alterations of different pancreatic zymogens or their inhibitors have been associated with chronic pancreatitis (CP).
We sequenced all 12 GP2 exons in 380 German CP patients and in 182 German control subjects. In addition, we analyzed exon 3 of GP2 in 803 further CP patients and 1780 controls originating from Germany, the Netherlands, and India by targeted DNA sequencing.
We detected 12 nonsynonymous and 6 synonymous exonic variants. All nonsynonymous changes with exception of c.220C>T (p.R74X) and c.502_503delG (p.G168fsX174) in exon 3 and c.541C>T (p.R181X) in exon 4 were missense mutations and predominantly located in exon 3. All nonsynonymous variants were found in single cases only, with exception of 2 alterations, c.355A>G (p.M119V) and c.409G>A (p. A137T), both located in exon 3. To elucidate the role of these 2 exon 3 variants, we investigated additional patients and controls. The frequency of these variants was similar between patients and controls regardless of ethnic background or cause of CP.
Our data suggest that GP2 alterations do not alter the risk for the development of CP.
[Show abstract][Hide abstract] ABSTRACT: Many candidate gene studies for atopic dermatitis (AD) and associated phenotypes have been conducted so far, but replication of significant results has been a major problem. Two loss of function polymorphisms FLG R501X- and 2282del4, in the Filaggrin (FLG) gene encoding for an epidermal barrier protein were recently identified. They were reported to be predisposing factors for AD and concomitant asthma. Several groups confirmed the initial results in independent populations. The aim of this study is to further investigate the importance of these FLG variants in the development of AD and subsequent asthma symptoms in pre-school children, we investigated children and parents of the Early Treatment of the Atopic Child (ETAC)-trial. We genotyped 496 children and 488 parents of the ETAC population for the two FLG variants, evaluating an association by family based analysis (transmission disequilibrium test). We found a highly significant association of the FLG null variants R501X- and 2282del4 with AD (combined genotype p < 0.0001) and asthma (combined genotype p < 0.0001). The replication and its statistical significance underlines the importance of the FLG polymorphisms and the importance of the skin barrier function in the development of AD and subsequent asthma.
Pediatric Allergy and Immunology 06/2009; 20(4):358-61. · 3.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Asthma prediction in early infancy is essential for the development of new preventive strategies. Loss-of-function mutations in the filaggrin gene (FLG) were identified as risk factors for eczema and associated asthma.
We evaluated the utility of the FLG mutations for the prediction of asthma.
Eight hundred seventy-one individuals of the prospective German Multicenter Allergy Study cohort were genotyped for 3 FLG mutations. Information on asthma, eczema, and food sensitization was available from birth to 13 years of age. Pulmonary function was measured from 7 to 13 years of age. The predictive value of the FLG mutations and of atopic phenotypes in infancy was assessed for asthma.
In infants with eczema and sensitization to food allergens, the FLG mutations predicted childhood asthma with a positive predictive value of 100% (95% CI, 65.5% to 100%). This subgroup was characterized by a significant decrease in pulmonary function until puberty and represented 8.1% of all asthmatic children and 19.1% of patients with asthma after infantile eczema. We found a strong synergistic interaction between the FLG-null alleles and early food sensitization in the disease transition from eczema to asthma (relative excess risk due to interaction, 2.64; 95% CI, 1.70-3.98; P = .00040).
FLG mutations and food sensitization represent 2 distinct mechanisms interacting in the pathogenesis of asthma. In infants with eczema and food sensitization, genotyping of the FLG mutations allows the prediction of asthma before the onset of symptoms. Our findings might facilitate the development of early subgroup-specific interventions to prevent the progression from eczema to asthma.
The Journal of allergy and clinical immunology 05/2009; 123(4):911-6. · 12.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The role of passive smoking for allergies and asthma in children above the age of 3 years remains unclear and possible interactive effects with parental allergies have not been formally evaluated in long-term studies. To examine the interaction of passive smoking and an allergic predisposition regarding allergic sensitization, allergic airway symptoms and respiratory infections during the first 10 years of life.
In a prospective multicenter birth cohort study with 1314 recruited children in Germany, we assessed serum immunoglobulin E against common allergens at seven time points, and parental smoking and respiratory symptoms annually by using questionnaires. Longitudinal analyses were performed using generalized estimating equation models (stratified by parental allergy status).
During the first 10 years, 18% of the children were exposed to regular maternal smoking since pregnancy, 43% to irregular maternal or only paternal smoking. Among children with two allergic parents, a mother who smoked regularly significantly increased the odds for allergic sensitization (adjusted OR 4.8, 95% CI 1.3-18.2) and wheezing (adjusted OR 5.7, 95% CI 1.7-19.0) in her child compared with children who were never exposed. For those with only one allergic parent, the odds were doubled and also statistically significant, whereas in children without allergic parents maternal smoking had no effects. There was no association of maternal smoking with allergic rhinitis or respiratory infections.
Our results suggest that regular maternal smoking is a strong risk factor for allergic sensitization and asthma symptoms during the first 10 years of life, but only in children with allergic parents.
[Show abstract][Hide abstract] ABSTRACT: Carriage of Neisseria meningitidis occurs approximately in 10% of the population, onset of invasive meningococcal disease (IMD) cannot be predicted and differs between ages. It remains unclear, which host factors determine invasion of the bloodstream by the bacteria. Innate immunity has a very important role in the first recognition of invading pathogens. The functional single nucleotide polymorphisms (SNPs) CD14 C-159T and toll-like receptor 4 (TLR4) Asp299Gly have been associated with the risk of gram-negative infections. However, their role in development of IMD still remains unclear. Our aim was to investigate the influence of CD14 C-159T and TLR4 Asp299Gly polymorphisms on the risk of IMD.
It was a retrospective case control study. Surviving Austrian meningococcal disease patients were enrolled by sending buccal swabs for DNA analysis. 185 cases with a proven meningococcal infection and 770 healthy controls were enrolled. In surviving meningococcal disease patients DNA analysis of CD14 C-159T and TLR 4 Asp299Gly polymorphisms was performed, as they are part of the innate immune response to bacterial determinants. CD14 C-159T and TLR4 Asp299Gly SNPs were not significantly associated with the presence of IMD when compared to healthy controls. The odds ratio for CD14 C-159T SNP was 1.14 (95% confidence interval (CI) 0.91-1.43; p = 0.266). In TLR4 Asp 299 Gly SNP the odds ratio was 0.78 (CI 0.47-1.43; p = 0.359).
We could not observe a significant influence of CD14 C-159T and TLR4 Asp299Gly polymorphisms on the risk of developing IMD in surviving meningococcal disease patients. To our knowledge, this is the first study investigating the influence of the CD14 C-159T SNP on the susceptibility to IMD.
PLoS ONE 01/2009; 4(10):e7374. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Increased total and specific serum immunoglobulin E (IgE) levels are common characteristics of atopic diseases and their basal production is proposed to be under strong genetic control. Interleukin 13 (IL13) variants have been consistently associated with total serum IgE levels in white populations with a strongest association in non-atopics. The aim of this study was to test the IL13 p.R130Q and c.1-1111C>T variants in children with atopic dermatitis (AD) for associations with total serum IgE and early sensitization to common food and inhalant allergens and with asthma. We included 453 children with AD [participants of the Early Treatment of the Atopic Child (ETAC) study] that were followed from the age of 12-24 months for 3 yr. Total and specific IgE were determined at four time points. We genotyped the IL13 p.R130Q and c.1-1111C>T variants by melting curve analysis. In children up to 4 yr of age, the 130Q allele was related to slightly higher total IgE levels compared to heterozygotes and 130R homozygotes. More importantly, both IL13 variants were significantly associated with sensitization to food allergens, with most significant results for sensitization to egg (p = 0.0001). Although early sensitization to hen's egg represents a strong risk factor for subsequent sensitization to inhalant allergens and asthma, the investigated IL13 variants were not associated with these phenotypes at the age of 48-60 months. In summary IL13 variants contribute to elevated levels of total serum IgE in young atopic children and are strongly associated with sensitization to food allergens, particularly to hen's egg. These findings suggest that IL13 variants play a major role not only in non-cognate but also in allergen specific IgE synthesis.
Pediatric Allergy and Immunology 01/2009; 20(6):551-5. · 3.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Asthma prevalence and severity are high among underserved minorities, including those of African descent. The Duffy antigen/receptor for chemokines is the receptor for Plasmodium vivax on erythrocytes and functions as a chemokine-clearing receptor. Unlike European populations, decreased expression of the receptor on erythrocytes is common among populations of African descent, and results from a functional T-46C polymorphism (rs2814778) in the promoter. This variant provides an evolutionary advantage in malaria-endemic regions, because Duffy antigen/receptor for chemokines-negative erythrocytes are more resistant to infection by P. vivax.
To determine the role of the rs2814778 polymorphism in asthma and atopy as measured by total serum IgE levels among four populations of African descent (African Caribbean, African American, Brazilian, and Colombian) and a European American population.
Family-based association tests were performed in each of the five populations to test for association between the rs2814778 polymorphism and asthma or total IgE concentration.
Asthma was significantly associated with the rs2814778 polymorphism in the African Caribbean, Colombian, and Brazilian families (P < 0.05). High total IgE levels were associated with this variant in African Caribbean and Colombian families (P < 0.05). The variant allele was not polymorphic among European Americans.
Susceptibility to asthma and atopy among certain populations of African descent is influenced by a functional polymorphism in the gene encoding Duffy antigen/receptor for chemokines. This genetic variant, which confers resistance to malarial parasitic infection, may also partially explain ethnic differences in morbidity of asthma.
American Journal of Respiratory and Critical Care Medicine 10/2008; 178(10):1017-22. · 11.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The inducible co-stimulatory molecule, ICOS, is an important regulator of T cell differentiation and effector function. Previously, it was reported that two variants in the ICOS promotor region, g.1-1413G>A and g.1-693G>A, were associated with sensitization to airborne allergens, elevated serum IgE levels and Th2 cytokine production in a Hutterite population. The aim of this study was to evaluate these two and four other selected ICOS variants for association with atopic phenotypes in two large European prospective pediatric cohorts. We investigated subjects from the German Multicenter Allergy Study (MAS), which followed over 800 children with atopic family history from birth until 13 yr of age, and from the Early Treatment of the Allergic Child Study (ETAC), which collected DNA and clinical data of over 330 children with atopic dermatitis during their first 2 yr of life. We genotyped DNA from these children by melting curve analysis using fluorescence resonance energy transfer (FRET) probes. We could not confirm the previously reported association of g.1-1413G>A and g.1-693G>A with atopic phenotypes in our pediatric cohorts. Also four other ICOS variants at putative binding sites for transcription factors showed no association with atopic dermatitis, asthma, allergic sensitization and allergic rhinitis. Our data suggest that these ICOS variants do not play a major role in the development of atopy in European children.
Pediatric Allergy and Immunology 10/2008; 20(3):242-5. · 3.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Childhood asthma is frequently perceived as a disease with uniform clinical pathways. This perception might be an oversimplification. The aim of the present study was to investigate the incidence and natural course of wheeze over the first 13 yrs of life and analyse the risk factors predicting wheeze at 11-13 yrs of age. The Multicentre Allergy Study, a German birth cohort, recruited 1,314 children in 1990. Physical examinations, interviews on atopic diseases, immunoglobulin (Ig)E and lung function tests were performed up to 13 yrs of age. Complete data on the course of wheeze were available for 441 children. It was found that incidence of wheezing declined with age. The first wheezing episode was reported by 29, 9 and 9% of participants at < or = 3 (early wheezers), 3-6 (late wheezers), and > 6 yrs (very late wheezers) of age, respectively. Wheezing at the age of 13 yrs was associated with parental atopy, and with IgE sensitisation to common allergens, elevated total IgE and exposure to high levels of indoor allergens in early life. All these associations were remarkably stronger among early wheezers than among early nonwheezers. In conclusion, the relevance of an early expression of atopy as a predictor of wheezing at age 13 yrs declines with increasing age of wheezing onset.
European Respiratory Journal 05/2008; 32(3):585-92. · 6.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A recent study reported that the c.30T>A (p.Cys10Ter; rs2043211) variant, in the CARD8 (TUCAN) gene, is associated with Crohn's disease (CD). The aim of this study was to analyze the frequency of p.C10X in 3 independent European (IBD) cohorts from Germany, Hungary, and the Netherlands.
We included a European IBD cohort of 921 patients and compared the p.C10X genotype frequency to 832 healthy controls. The 3 study populations analyzed were: (1) Germany [CD, n = 317; ulcerative colitis (UC), n = 180], (2) Hungary (CD, n = 149; UC, n = 119), and (3) the Netherlands (CD, n = 156). Subtyping analysis was performed in respect to NOD2 variants (p.Arg702Trp, p.Gly908Arg, c.3020insC) and to clinical characteristics. Ethnically matched controls were included (German, n = 413; Hungarian, n = 202; Dutch, n = 217).
We observed no significant difference in p.C10X genotype frequency in either patients with CD or patients with UC compared with controls in all 3 cohorts. Conversely to the initial association study, we found a trend toward lower frequencies of the suggestive risk wild type in CD from the Netherlands compared with controls (P = 0.14). We found neither evidence for genetic interactions between p.C10X and NOD2 nor the C10X variant to be associated with a CD or UC phenotype.
Analyzing 3 independent European IBD cohorts, we found no evidence that the C10X variant in CARD8 confers susceptibility for CD.
[Show abstract][Hide abstract] ABSTRACT: Primary prevention strategies of allergy so far have been aimed to fight allergy causes, by avoiding risk factors and inhibiting their mechanisms of action. The results of trials testing food or airborne allergen avoidance as a prevention strategy were, however, rather disappointing. A reverse approach for primary prevention of allergies aims to facilitate exposure to protecting factors which promote the induction of immunologic tolerance against innocuous antigens. These factors are associated with farming environment and a 'traditional lifestyle', but identification of these factors is quite difficult. Major candidates include food-borne microbes, helminths or their components, which are able to stimulate mucosal immunity, particularly in the gut. Similarly, new preventive and therapeutic strategies are being tested to induce specific food-allergen oral tolerance through the ingestion of progressively increasing doses of the offending food. This shifting of allergy prevention research from avoidance to tolerance induction will hopefully allow us to reverse the epidemic trend of allergy diseases.
[Show abstract][Hide abstract] ABSTRACT: Chronic pancreatitis is a persistent inflammatory disease of the pancreas, in which the digestive protease trypsin has a fundamental pathogenetic role. Here we have analyzed the gene encoding the trypsin-degrading enzyme chymotrypsin C (CTRC) in German subjects with idiopathic or hereditary chronic pancreatitis. Two alterations in this gene, p.R254W and p.K247_R254del, were significantly overrepresented in the pancreatitis group, being present in 30 of 901 (3.3%) affected individuals but only 21 of 2,804 (0.7%) controls (odds ratio (OR) = 4.6; confidence interval (CI) = 2.6-8.0; P = 1.3 x 10(-7)). A replication study identified these two variants in 10 of 348 (2.9%) individuals with alcoholic chronic pancreatitis but only 3 of 432 (0.7%) subjects with alcoholic liver disease (OR = 4.2; CI = 1.2-15.5; P = 0.02). CTRC variants were also found in 10 of 71 (14.1%) Indian subjects with tropical pancreatitis but only 1 of 84 (1.2%) healthy controls (OR = 13.6; CI = 1.7-109.2; P = 0.0028). Functional analysis of the CTRC variants showed impaired activity and/or reduced secretion. The results indicate that loss-of-function alterations in CTRC predispose to pancreatitis by diminishing its protective trypsin-degrading activity.
[Show abstract][Hide abstract] ABSTRACT: The lipopolysaccharide (LPS)-triggered release of inflammatory cytokines from Kupffer cells is mediated via the CD14/TLR4 receptor complex. This inflammatory pathway can be influenced by alterations in genes encoding for LPS receptor components. Thus, a -260 C>T transition in the CD14 promoter is thought to result in enhanced CD14 expression thereby increasing the LPS responsiveness in chronic liver diseases, whereas a D299G exchange in the TLR4 gene has the opposite effect. Our objective was to analyze these two variations.
The study comprised 1712 patients with chronic liver diseases of different etiologies and 385 healthy controls. Genotyping was carried out by melting curve analysis with fluorescence resonance energy transfer (FRET) probes in the LightCycler.
Genotype frequencies of CD14 -260C>T and TLR4 D299G did not significantly differ between patients and controls (CD14 TT 21.6% versus 21.8%; TLR4 DG or GG 9.7% versus 10.4%). We found no significant correlation of these alterations with disease course either in the groups of patients with alcoholic liver disease or hepatitis C virus (HCV) infection or among patients requiring liver transplantation. A significantly higher frequency of the CD14 -260TT genotype was observed (36.6% versus 21.8% in healthy controls, p=0.036) only in a small subgroup of patients (n=41) with mild cryptogenic chronic liver disease.
Variants within these LPS receptor genes were equally distributed among patients with chronic liver diseases of different etiologies and obviously do not confer an increased risk for the severity of these chronic liver processes.
Scandinavian Journal of Gastroenterology 01/2008; 43(5):584-92. · 2.33 Impact Factor