RESUMO
Variants associated with meconium ileus in cystic fibrosis were identified in 3,763 affected individuals by genome-wide association study (GWAS). Five SNPs at two loci near SLC6A14 at Xq23-24 (minimum P = 1.28 × 10(-12) at rs3788766) and SLC26A9 at 1q32.1 (minimum P = 9.88 × 10(-9) at rs4077468) accounted for ~5% of phenotypic variability and were replicated in an independent sample of affected individuals (n = 2,372; P = 0.001 and 0.0001, respectively). By incorporating the knowledge that disease-causing mutations in CFTR alter electrolyte and fluid flux across surface epithelium into a hypothesis-driven GWAS (GWAS-HD), we identified associations with the same SNPs in SLC6A14 and SLC26A9 and established evidence for the involvement of SNPs in a third solute carrier gene, SLC9A3. In addition, GWAS-HD provided evidence of association between meconium ileus and multiple genes encoding constituents of the apical plasma membrane where CFTR resides (P = 0.0002; testing of 155 apical membrane genes jointly and in replication, P = 0.022). These findings suggest that modulating activities of apical membrane constituents could complement current therapeutic paradigms for cystic fibrosis.
Assuntos
Membrana Celular/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Fibrose Cística/genética , Predisposição Genética para Doença , Íleus/genética , Mecônio , Polimorfismo de Nucleotídeo Único/genética , Sistemas de Transporte de Aminoácidos , Sistemas de Transporte de Aminoácidos Neutros/genética , Antiporters/genética , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Obstrução Intestinal/etiologia , Trocador 3 de Sódio-Hidrogênio , Trocadores de Sódio-Hidrogênio/genética , Transportadores de SulfatoRESUMO
Meconium ileus (MI), a life-threatening intestinal obstruction due to meconium with abnormal protein content, occurs in approximately 15 percent of neonates with cystic fibrosis (CF). Analysis of twins with CF demonstrates that MI is a highly heritable trait, indicating that genetic modifiers are largely responsible for this complication. Here, we performed regional family-based association analysis of a locus that had previously been linked to MI and found that SNP haplotypes 5' to and within the MSRA gene were associated with MI (Pâ=â1.99 × 10(-5) to 1.08 × 10(-6); Bonferroni Pâ=â0.057 to 3.1 × 10(-3)). The haplotype with the lowest P value showed association with MI in an independent sample of 1,335 unrelated CF patients (ORâ=â0.72, 95% CI [0.53-0.98], Pâ=â0.04). Intestinal obstruction at the time of weaning was decreased in CF mice with Msra null alleles compared to those with wild-type Msra resulting in significant improvement in survival (Pâ=â1.2 × 10(-4)). Similar levels of goblet cell hyperplasia were observed in the ilea of the Cftr(-/-) and Cftr(-/-)Msra(-/-) mice. Modulation of MSRA, an antioxidant shown to preserve the activity of enzymes, may influence proteolysis in the developing intestine of the CF fetus, thereby altering the incidence of obstruction in the newborn period. Identification of MSRA as a modifier of MI provides new insight into the biologic mechanism of neonatal intestinal obstruction caused by loss of CFTR function.
Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística , Fibrose Cística , Obstrução Intestinal , Metionina Sulfóxido Redutases , Animais , Fibrose Cística/complicações , Fibrose Cística/genética , Fibrose Cística/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Estudos de Associação Genética , Células Caliciformes/patologia , Haplótipos , Humanos , Obstrução Intestinal/complicações , Obstrução Intestinal/genética , Obstrução Intestinal/metabolismo , Metionina Sulfóxido Redutases/genética , Metionina Sulfóxido Redutases/metabolismo , Camundongos , Camundongos Endogâmicos CFTR , Polimorfismo de Nucleotídeo ÚnicoRESUMO
OBJECTIVE: To quantify the relative contribution of factors other than cystic fibrosis transmembrane conductance regulator genotype and environment on the acquisition of Pseudomonas aeruginosa (Pa) by patients with cystic fibrosis. STUDY DESIGN: Lung infection with Pa and mucoid Pa was assessed using a co-twin study design of 44 monozygous (MZ) and 17 dizygous (DZ) twin pairs. Two definitions were used to establish infection: first positive culture and persistent positive culture. Genetic contribution to infection (ie, heritability) was estimated based on concordance analysis, logistic regression, and age at onset of infection through comparison of intraclass correlation coefficients. RESULTS: Concordance for persistent Pa infection was higher in MZ (0.83; 25 of 30 pairs) than DZ twins (0.45; 5 of 11 pairs), generating a heritability of 0.76. Logistic regression adjusted for age corroborated genetic control of persistent Pa infection. The correlation for age at persistent Pa infection was higher in MZ twins (0.589; 95% CI, 0.222-0.704) than in DZ twins (0.162; 95% CI, -0.352 to 0.607), generating a heritability of 0.85. CONCLUSION: Genetic modifiers play a significant role in the establishment and timing of persistent Pa infection in individuals with cystic fibrosis.
Assuntos
Fibrose Cística/genética , Doenças em Gêmeos/genética , Genes Modificadores/genética , Infecções por Pseudomonas/genética , Pseudomonas aeruginosa , Infecções Respiratórias/genética , Adolescente , Criança , Pré-Escolar , Fibrose Cística/microbiologia , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Epistasia Genética , Feminino , Humanos , Masculino , Infecções por Pseudomonas/complicações , Infecções Respiratórias/complicações , Gêmeos Dizigóticos , Gêmeos MonozigóticosRESUMO
BACKGROUND: Progressive lung disease accounts for the majority of morbidity and mortality observed in cystic fibrosis (CF). Beyond secondhand smoke exposure and socio-economic status, the effect of specific environmental factors on CF lung function is largely unknown. METHODS: Multivariate regression was used to assess correlation between specific environmental factors, the presence of pulmonary pathogens, and variation in lung function using subjects enrolled in the U.S. CF Twin and Sibling Study (CFTSS: nâ=â1378). Significant associations were tested for replication in the U.S. CF Foundation Patient Registry (CFF: nâ=â16439), the Australian CF Data Registry (ACFDR: nâ=â1801), and prospectively ascertained subjects from Australia/New Zealand (ACFBAL: nâ=â167). RESULTS: In CFTSS subjects, the presence of Pseudomonas aeruginosa (ORâ=â1.06 per °F; p<0.001) was associated with warmer annual ambient temperatures. This finding was independently replicated in the CFF (1.02; p<0.001), ACFDR (1.05; pâ=â0.002), and ACFBAL (1.09; pâ=â0.003) subjects. Warmer temperatures (-0.34 points per °F; pâ=â0.005) and public insurance (-6.43 points; p<0.001) were associated with lower lung function in the CFTSS subjects. These findings were replicated in the CFF subjects (temperature: -0.31; p<0.001; insurance: -9.11; p<0.001) and similar in the ACFDR subjects (temperature: -0.23; pâ=â0.057). The association between temperature and lung function was minimally influenced by P. aeruginosa. Similarly, the association between temperature and P. aeruginosa was largely independent of lung function. CONCLUSIONS: Ambient temperature is associated with prevalence of P. aeruginosa and lung function in four independent samples of CF patients from two continents.
Assuntos
Infecções Bacterianas/fisiopatologia , Fibrose Cística/fisiopatologia , Pulmão/fisiopatologia , Temperatura , Infecções Bacterianas/complicações , Complexo Burkholderia cepacia/isolamento & purificação , Estudos de Coortes , Fibrose Cística/complicações , Feminino , Humanos , Estimativa de Kaplan-Meier , Modelos Logísticos , Pulmão/microbiologia , Pulmão/patologia , Masculino , Pseudomonas aeruginosa/isolamento & purificação , Sistema de Registros/estatística & dados numéricosRESUMO
A combined genome-wide association and linkage study was used to identify loci causing variation in cystic fibrosis lung disease severity. We identified a significant association (P = 3.34 × 10(-8)) near EHF and APIP (chr11p13) in p.Phe508del homozygotes (n = 1,978). The association replicated in p.Phe508del homozygotes (P = 0.006) from a separate family based study (n = 557), with P = 1.49 × 10(-9) for the three-study joint meta-analysis. Linkage analysis of 486 sibling pairs from the family based study identified a significant quantitative trait locus on chromosome 20q13.2 (log(10) odds = 5.03). Our findings provide insight into the causes of variation in lung disease severity in cystic fibrosis and suggest new therapeutic targets for this life-limiting disorder.
Assuntos
Cromossomos Humanos Par 11 , Cromossomos Humanos Par 20 , Fibrose Cística/genética , Ligação Genética , Pneumopatias/genética , Adolescente , Adulto , Criança , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , Fenótipo , Locos de Características QuantitativasRESUMO
BACKGROUND: Lung infection by various organisms is a characteristic feature of cystic fibrosis (CF). CFTR genotype effects acquisition of Pseudomonas aeruginosa (Pa), however the effect on acquisition of other infectious organisms that frequently precede Pa is relatively unknown. Understanding the role of CFTR in the acquisition of organisms first detected in patients may help guide symptomatic and molecular-based treatment for CF. METHODS: Lung infection, defined as a single positive respiratory tract culture, was assessed for 13 organisms in 1,381 individuals with CF. Subjects were divided by predicted CFTR function: 'Residual': carrying at least one partial function CFTR mutation (class IV or V) and 'Minimal' those who do not carry a partial function mutation. Kaplan-Meier estimates were created to assess CFTR effect on age of acquisition for each organism. Cox proportional hazard models were performed to control for possible cofactors. A separate Cox regression was used to determine whether defining infection with Pa, mucoid Pa or Aspergillus (Asp) using alternative criteria affected the results. The influence of severity of lung disease at the time of acquisition was evaluated using stratified Cox regression methods by lung disease categories. RESULTS: Subjects with 'Minimal' CFTR function had a higher hazard than patients with 'Residual' function for acquisition of 9 of 13 organisms studied (HR ranging from 1.7 to 3.78 based on the organism studied). Subjects with minimal CFTR function acquired infection at a younger age than those with residual function for 12 of 13 organisms (p-values ranging: < 0.001 to 0.017). Minimal CFTR function also associated with younger age of infection when 3 alternative definitions of infection with Pa, mucoid Pa or Asp were employed. Risk of infection is correlated with CFTR function for 8 of 9 organisms in patients with good lung function (>90%ile) but only 1 of 9 organisms in those with poorer lung function (<50%ile). CONCLUSIONS: Residual CFTR function correlates with later onset of respiratory tract infection by a wide spectrum of organisms frequently cultured from CF patients. The protective effect conferred by residual CFTR function is diminished in CF patients with more advanced lung disease.
Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/genética , Fibrose Cística/genética , Fibrose Cística/metabolismo , Mutação/genética , Infecções Respiratórias/genética , Adolescente , Adulto , Criança , Pré-Escolar , Fibrose Cística/microbiologia , Regulador de Condutância Transmembrana em Fibrose Cística/fisiologia , Feminino , Seguimentos , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/microbiologia , Adulto JovemRESUMO
RATIONALE: Individuals with cystic fibrosis (CF) are subject to recurrent respiratory infections (exacerbations) that often require intravenous antibiotic treatment and may result in permanent loss of lung function. The optimal means of delivering therapy remains unclear. OBJECTIVES: To determine whether duration or venue of intravenous antibiotic administration affect lung function. METHODS: Data were retrospectively collected on 1,535 subjects recruited by the US CF Twin and Sibling Study from US CF care centers between 2000 and 2007. MEASUREMENTS AND MAIN RESULTS: Long-term decline in FEV1 after exacerbation was observed regardless of whether antibiotics were administered in the hospital (mean, -3.3 percentage points [95% confidence interval, -3.9 to -2.6]; n = 602 courses of therapy) or at home (mean, -3.5 percentage points [95% confidence interval, -4.5 to -2.5]; n = 232 courses of therapy); this decline was not different by venue using t tests (P = 0.69) or regression (P = 0.91). No difference in intervals between courses of antibiotics was observed between hospital (median, 119 d [interquartile range, 166]; n = 602) and home (median, 98 d [interquartile range, 155]; n = 232) (P = 0.29). Patients with greater drops in FEV1 with exacerbations had worse long-term decline even if lung function initially recovered with treatment (P < 0.001). Examination of FEV1 measures obtained during treatment for exacerbations indicated that improvement in FEV1 plateaus after 7-10 days of therapy. CONCLUSIONS: Intravenous antibiotic therapy for CF respiratory exacerbations administered in the hospital and in the home was found to be equivalent in terms of long-term FEV1 change and interval between courses of antibiotics. Optimal duration of therapy (7-10 d) may be shorter than current practice. Large prospective studies are needed to answer these essential questions for CF respiratory management.
Assuntos
Antibacterianos/administração & dosagem , Fibrose Cística/tratamento farmacológico , Hospitalização , Ambulatório Hospitalar , Adolescente , Assistência Ambulatorial , Criança , Fibrose Cística/fisiopatologia , Progressão da Doença , Feminino , Volume Expiratório Forçado , Humanos , Infusões Intravenosas , Tempo de Internação , Masculino , Recidiva , Estudos Retrospectivos , Resultado do Tratamento , Estados Unidos , Adulto JovemRESUMO
OBJECTIVE: To assess the relative contributions of environmental and genetic factors to variation in cystic fibrosis (CF) lung disease. STUDY DESIGN: Genetic and environmental contributions were quantified by use of intrapair correlations and differences in CF-specific forced expiratory volume in 1 second measures from 134 monozygous twins and 272 dizygous twins and siblings while in different living environments (ie, living with parents vs living alone), as well as by use of intraindividual differences in pulmonary function from a separate group of 80 siblings. RESULTS: Pulmonary function among monozygous twins was more similar than among dizygous twin and sibling pairs, regardless of living environment, affirming the role of genetic modifiers in CF pulmonary function. Regression modeling revealed that genetic factors account for 50% of pulmonary function variation, unique environmental or stochastic factors (36%), and shared environmental factors (14%; P < .0001). The intraindividual analysis produced similar estimates for the contributions of the unique and shared environment. The shared environment effects appeared primarily because of living with a sibling with CF (P = .003), rather than factors within the parental household (P = .310). CONCLUSIONS: Genetic and environmental factors contribute equally to pulmonary function variation in CF. Environmental effects are dominated by unique and stochastic effects rather than common exposures.
Assuntos
Fibrose Cística/etiologia , Fibrose Cística/fisiopatologia , Pulmão/fisiopatologia , Adolescente , Adulto , Criança , Fibrose Cística/genética , Meio Ambiente , Feminino , Predisposição Genética para Doença , Humanos , Masculino , Adulto JovemRESUMO
Cystic fibrosis (CF), the most common lethal single gene disorder in Caucasians, is due to mutations in the CFTR gene. Twin and sibling analysis indicates that modifier genes, rather than allelic variation in CFTR, are responsible for most of the variability in severity of lung disease, the major cause of mortality in CF patients. We used a family-based approach to test for association between lung function and two functional SNPs (rs1800469, '-509' and rs1982073, 'codon 10') in the 5' region of transforming growth factor-beta1 (TGFB1), a putative CF modifier gene. Quantitative transmission disequilibrium testing of 472 CF patient-parent-parent trios revealed that both TGFB1 SNPs showed significant transmission distortion when patients were stratified by CFTR genotype. Although lung function and nutritional status are correlated in CF patients, there was no evidence of association between the TGFB1 SNPs and variation in nutritional status. Additional tagging SNPs (rs8179181, rs2278422, rs8110090, rs4803455 and rs1982072) that capture most of the diversity in TGFB1 were also typed but none showed association with variation in lung function. However, a haplotype composed of the -509 C and codon 10 T alleles along with the C allele of the 3' SNP rs8179181 was highly associated with increased lung function in patients grouped by CFTR genotype. These results demonstrate that TGFB1 is a modifier of CF lung disease and reveal a previously unrecognized beneficial effect of TGFB1 variants upon the pulmonary phenotype.