title: Investigation of the genetic overlap between rheumatoid arthritis and psoriatic arthritis in a Greek population.
abstract: OBJECTIVE
  Several rheumatoid arthritis (RA) susceptibility loci have also been found to be associated with psoriatic arthritis (PsA), demonstrating that there is a degree of genetic overlap between various autoimmune diseases. We sought to investigate whether single nucleotide polymorphisms (SNPs) mapping to previously reported RA and/or PsA susceptibility loci, including PLCL2, CCL21, REL, STAT4, CD226, PTPN22, and TYK2, are associated with risk for the two diseases in a genetically homogeneous Greek population.
  
  
  METHODS
  This study included 392 RA patients, 126 PsA patients, and 521 healthy age- and sex-matched controls from Greece. Genotyping of the SNPs was performed with Taqman primer/probe sets. Bioinformatic analysis was performed using BlastP, PyMOL, and Maestro and Desmond.
  
  
  RESULTS
  A significant association was detected between the GC genotype of rs34536443 (TYK2) in both the PsA and RA cohorts. The C allele of this SNP was associated with PsA only. Evidence for association with PsA was also found for the GG genotype and G allele of the rs10181656 SNP of STAT4. The TC genotype of the rs763361 SNP of CD226 was associated with PsA only.
  
  
  CONCLUSIONS
  Genetic overlap between PsA and RA was detected for the rs34536443 SNP of the TYK2 gene within a Greek population. An association of STAT4 (rs10181656) with PsA was confirmed whereas CD226 (rs763361) was associated with PsA but not with RA, in contrast to previous reports. The different findings of this study compared to previous ones highlights the importance of comparative studies that include various ethnic or racial populations.
authors.affiliation: a Laboratory of Molecular Medicine and Human Genetics, Department of Internal Medicine , School of Medicine, University of Crete , Heraklion , Greece.
authors.forename: E
authors.initials: E
authors.lastname: Myrthianou
authors.affiliation: a Laboratory of Molecular Medicine and Human Genetics, Department of Internal Medicine , School of Medicine, University of Crete , Heraklion , Greece.
authors.forename: M I
authors.initials: MI
authors.lastname: Zervou
authors.affiliation: b Arthritis Research UK Centre for Genetics and Genomics, Centre for Musculoskeletal Research , Institute for Inflammation and Repair, Manchester Academic Health Science Centre, The University of Manchester , Manchester , UK.|c NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre , Manchester , UK.
authors.forename: A
authors.initials: A
authors.lastname: Budu-Aggrey
authors.affiliation: d Laboratory of Genetics, Department of Biotechnology , Agricultural University of Athens , Athens , Greece.
authors.forename: E
authors.initials: E
authors.lastname: Eliopoulos
authors.affiliation: e Department of Biochemistry , School of Medicine, University of Crete and Institute of Molecular Biology and Biotechnology of Crete , Heraklion , Greece.|f Institute of Molecular Biology and Biotechnology, FORTH , Heraklion , Crete , Greece.
authors.forename: D
authors.initials: D
authors.lastname: Kardassis
authors.affiliation: f Institute of Molecular Biology and Biotechnology, FORTH , Heraklion , Crete , Greece.|g Faculty of Medicine , University of Athens , Athens , Greece.
authors.forename: D T
authors.initials: DT
authors.lastname: Boumpas
authors.affiliation: h Department of Rheumatology, Clinical Immunology and Allergy, Faculty of Medicine , University of Crete , Heraklion , Greece.
authors.forename: N
authors.initials: N
authors.lastname: Kougkas
authors.affiliation: b Arthritis Research UK Centre for Genetics and Genomics, Centre for Musculoskeletal Research , Institute for Inflammation and Repair, Manchester Academic Health Science Centre, The University of Manchester , Manchester , UK.|c NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre , Manchester , UK.|i The Kellgren Centre for Rheumatology, Central Manchester Foundation Trust, NIHR Manchester Biomedical Research Centre , Manchester , UK.
authors.forename: A
authors.initials: A
authors.lastname: Barton
authors.affiliation: h Department of Rheumatology, Clinical Immunology and Allergy, Faculty of Medicine , University of Crete , Heraklion , Greece.
authors.forename: P
authors.initials: P
authors.lastname: Sidiropoulos
authors.affiliation: a Laboratory of Molecular Medicine and Human Genetics, Department of Internal Medicine , School of Medicine, University of Crete , Heraklion , Greece.
authors.forename: G N
authors.initials: GN
authors.lastname: Goulielmos
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics; D015535:Arthritis, Psoriatic / Q000235:genetics*; D001172:Arthritis, Rheumatoid / Q000235:genetics*; D016022:Case-Control Studies; D054421:Chemokine CCL21 / Q000235:genetics; D015331:Cohort Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D060005:Genotyping Techniques; D006115:Greece; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D020572:Oncogene Proteins v-rel / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22 / Q000235:genetics; D050797:STAT4 Transcription Factor / Q000235:genetics; D053634:TYK2 Kinase / Q000235:genetics; D044465:White People / Q000235:genetics*; D000098862:T Lineage-Specific Activation Antigen 1
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; C515478:CCL21 protein, human; D000098862:T Lineage-Specific Activation Antigen 1; D054421:Chemokine CCL21; D047908:Intracellular Signaling Peptides and Proteins; D020572:Oncogene Proteins v-rel; C530632:PLCL2 protein, human; D050797:STAT4 Transcription Factor; C494090:STAT4 protein, human; D053634:TYK2 Kinase; C070139:TYK2 protein, human; C516765:PTPN22 protein, human; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22