title: Clinical and molecular characterization of the potential CF disease modifier syntaxin 1A.
abstract: Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator gene (CFTR). Disease severity in CF varies greatly, and sibling studies strongly indicate that genes other than CFTR modify disease outcome. Syntaxin 1A (STX1A) has been reported as a negative regulator of CFTR and other ion channels. We hypothesized that STX1A variants act as a CF modifier by influencing the remaining function of mutated CFTR. We identified STX1A variants by genomic resequencing patients from the Bernese CF Patient Data Registry and applied linear mixed model analysis to establish genotype-phenotype correlations, revealing STX1A rs4363087 (c.467-38A>G) to significantly influence lung function. The same STX1A risk allele was recognized in the European CF Twin and Sibling Study (P=0.0027), demonstrating that the genotype-phenotype association of STX1A to CF disease severity is robust enough to allow replication in two independent CF populations. rs4363087 is in linkage disequilibrium to the exonic variant rs2228607 (c.204C>T). Considering that neither rs4363087 nor rs2228607 changes the amino-acid sequence of STX1A, we investigated their effects on mRNA level. We show that rs2228607 reinforces aberrant splicing of STX1A mRNA, leading to nonsense-mediated mRNA decay. In conclusion, we demonstrate the clinical relevance of STX1A variants in CF, and evidence the functional relevance of STX1A variant rs2228607 at molecular level. Our findings show that genes interacting with CFTR can modify CF disease progression.
authors.affiliation: Division of Human Genetics, Departments of Pediatrics and Clinical Research, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: von Kanel
authors.forename: Frauke
authors.initials: F
authors.lastname: Stanke
authors.forename: Melanie
authors.initials: M
authors.lastname: Weber
authors.forename: Andre
authors.initials: A
authors.lastname: Schaller
authors.forename: Julien
authors.initials: J
authors.lastname: Racine
authors.forename: Richard
authors.initials: R
authors.lastname: Kraemer
authors.forename: Marc
authors.initials: M
authors.lastname: Chanson
authors.forename: Burkhard
authors.initials: B
authors.lastname: Tümmler
authors.forename: Sabina
authors.initials: S
authors.lastname: Gallati
mesh_terms: D000293:Adolescent; D000483:Alleles; D002648:Child; D003550:Cystic Fibrosis / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics; D056914:Genomic Structural Variation / Q000235:genetics; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium / Q000235:genetics; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics; D050827:Syntaxin 1 / Q000235:genetics*; D055815:Young Adult
chemical_list: D012333:RNA, Messenger; C494212:STX1A protein, human; D050827:Syntaxin 1; D019005:Cystic Fibrosis Transmembrane Conductance Regulator