title: A common 56-kilobase deletion in a primate-specific segmental duplication creates a novel butyrophilin-like protein.
abstract: BACKGROUND
  The Butyrophilin-like (BTNL) proteins are likely to play an important role in inflammation and immune response. Like the B7 protein family, many human and murine BTNL members have been shown to control T lymphocytes response, and polymorphisms in human BTNL2 have been linked to several inflammatory diseases, such as pulmonary sarcoidosis, inflammatory bowel disease and neonatal lupus.
  
  
  RESULTS
  In this study we provide a comprehensive population, genomic and transcriptomic analysis of a 56-kb deletion copy number variant (CNV), located within two segmental duplications of two genes belonging to the BTNL family, namely BTNL8 and BTNL3. We confirm the presence of a novel BTNL8*3 fusion-protein product, and show an influence of the deletion variant on the expression level of several genes involved in immune function, including BTNL9, another member of the same family. Moreover, by genotyping HapMap and human diversity panel (HGDP) samples, we demonstrate a clear difference in the stratification of the BTNL8_BTNL3-del allele frequency between major continental human populations.
  
  
  CONCLUSIONS
  Despite tremendous progress in the field of structural variation, rather few CNVs have been functionally characterized so far. Here, we show clear functional consequences of a new deletion CNV (BTNL8_BTNL3-del) with potentially important implication in the human immune system and in inflammatory and proliferative disorders. In addition, the marked population differences found of BTNL8_BTNL3-del frequencies suggest that this deletion CNV might have evolved under positive selection due to environmental conditions in some populations, with potential phenotypic consequences.
authors.affiliation: Bioinformatics and Genomics Program, Centre for Genomic Regulation (CRG), Barcelona 08003, Spain.
authors.forename: Johanna
authors.initials: J
authors.lastname: Aigner
authors.forename: Sergi
authors.initials: S
authors.lastname: Villatoro
authors.forename: Raquel
authors.initials: R
authors.lastname: Rabionet
authors.forename: Jaume
authors.initials: J
authors.lastname: Roquer
authors.forename: Jordi
authors.initials: J
authors.lastname: Jiménez-Conde
authors.forename: Eulàlia
authors.initials: E
authors.lastname: Martí
authors.forename: Xavier
authors.initials: X
authors.lastname: Estivill
mesh_terms: D000483:Alleles; D000818:Animals; D001483:Base Sequence; D000071797:Butyrophilins; D055028:Comparative Genomic Hybridization; D004247:DNA / Q000235:genetics; D006801:Humans; D015810:Linkage Disequilibrium; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D020641:Polymorphism, Single Nucleotide; D011323:Primates / Q000235:genetics*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
chemical_list: D000071797:Butyrophilins; D008562:Membrane Glycoproteins; D004247:DNA