title: Distinct genetic risk based on association of MET in families with co-occurring autism and gastrointestinal conditions.
abstract: OBJECTIVE
  In addition to the core behavioral symptoms of autism spectrum disorder, many patients present with complex medical conditions including gastrointestinal dysfunction. A functional variant in the promoter of the gene encoding the MET receptor tyrosine kinase is associated with autism spectrum disorder, and MET protein expression is decreased in the temporal cortex of subjects with autism spectrum disorder. MET is a pleiotropic receptor that functions in both brain development and gastrointestinal repair. On the basis of these functions, we hypothesized that association of the autism spectrum disorder-associated MET promoter variant may be enriched in a subset of individuals with co-occurring autism spectrum disorder and gastrointestinal conditions.
  
  
  METHODS
  Subjects were 918 individuals from 214 Autism Genetics Resource Exchange families with a complete medical history including gastrointestinal condition report. Genotypes at the autism spectrum disorder-associated MET promoter variant rs1858830 were determined. Family-based association test and chi(2) analyses were used to determine the association of MET rs1858830 alleles with autism spectrum disorder and the presence of gastrointestinal conditions.
  
  
  RESULTS
  In the entire 214-family sample, the MET rs1858830 C allele was associated with both autism spectrum disorder and gastrointestinal conditions. Stratification by the presence of gastrointestinal conditions revealed that the MET C allele was associated with both autism spectrum disorder and gastrointestinal conditions in 118 families containing at least 1 child with co-occurring autism spectrum disorder and gastrointestinal conditions. In contrast, there was no association of the MET polymorphism with autism spectrum disorder in the 96 families lacking a child with co-occurring autism spectrum disorder and gastrointestinal conditions. chi(2) analyses of MET rs1858830 genotypes indicated over-representation of the C allele in individuals with co-occurring autism spectrum disorder and gastrointestinal conditions compared with non-autism spectrum disorder siblings, parents, and unrelated controls.
  
  
  CONCLUSIONS
  These results suggest that disrupted MET signaling may contribute to increased risk for autism spectrum disorder that includes familial gastrointestinal dysfunction.
authors.affiliation: Vanderbilt University, 8114 MRB3, 465 21st Ave South, Nashville, TN 37232, USA. daniel.campbell@vanderbilt.edu
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Campbell
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Buie
authors.forename: Harland
authors.initials: H
authors.lastname: Winter
authors.forename: Margaret
authors.initials: M
authors.lastname: Bauman
authors.forename: James S
authors.initials: JS
authors.lastname: Sutcliffe
authors.forename: James M
authors.initials: JM
authors.lastname: Perrin
authors.forename: Pat
authors.initials: P
authors.lastname: Levitt
mesh_terms: D000483:Alleles; D001321:Autistic Disorder / Q000235:genetics*; D002648:Child; D015897:Comorbidity; D005260:Female; D005767:Gastrointestinal Diseases / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019859:Proto-Oncogene Proteins c-met; D017978:Receptors, Growth Factor / Q000235:genetics*; D012307:Risk Factors; D015398:Signal Transduction / Q000235:genetics
chemical_list: D011518:Proto-Oncogene Proteins; D017978:Receptors, Growth Factor; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met