Rheumatoid arthritis does not share most of the newly identified systemic lupus erythematosus genetic factors.
OBJECTIVE
Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) share some genetic factors such as HLA, PTPN22, STAT4, and 6q23. The aim of this study was to determine whether 9 other SLE genetic factors are also implicated in RA susceptibility.


METHODS
A characteristic single-nucleotide polymorphism (SNP) in each of 9 genetic factors, ITGAM (rs1143679), C8orf13-BLK (rs13277113), TYK2 (rs2304256), 1q25.1 (rs10798269), PXK (rs6445975), KIAA1542 (rs4963128), MECP2 (rs17435), BANK1 (rs17266594), and LY9 (rs509749), was studied in 1,635 patients with RA and 1,906 control subjects from Spain. The rs7574865 SNP in STAT4 was also included. Analyses were conducted globally and after stratification by sex and clinical features (anti-cyclic citrullinated peptide and rheumatoid factor, shared epitope, rheumatoid nodules, radiographic changes, sicca syndrome, and pneumonitis).


RESULTS
No association was observed between RA and any of the 9 newly identified SLE genetic factors. A meta-analysis using previous data was consistent with these results. In addition, there were no significant differences between individuals with and those without each of the clinical features analyzed, except the frequency of the minor allele in the C8orf13-BLK locus that was decreased in patients with sicca syndrome (14.6% versus 22.4% in controls; P = 0.003).


CONCLUSIONS
None of the 9 recently identified SLE risk factors showed association with RA. Therefore, common genetic factors affecting the pathogenesis of these 2 disorders seem to be limited, revealing that the genetic component contributes to the different expression of these diseases.
Suarez-Gestal
Marian
M
Hospital Clinico Universitario de Santiago, Travesia de Choupana s/n, Santiago de Compostela, Spain.
Calaza
Manuel
M
Dieguez-Gonzalez
Rebeca
R
Perez-Pampin
Eva
E
Pablos
Jose Luis
JL
Navarro
Federico
F
Narvaez
Javier
J
Marenco
Jose Luis
JL
Herrero-Beaumont
Gabriel
G
Fernandez-Gutierrez
Benjamin
B
Lamas
Jose Ramon
JR
de la Serna
Arturo Rodriguez
AR
Ortiz
Ana Maria
AM
Carreño
Luis
L
Cañete
Juan D
JD
Caliz
Rafael
R
Blanco
Francisco J
FJ
Balsa
Alejandro
A
Gomez-Reino
Juan J
JJ
Gonzalez
Antonio
A
D000328:Adult; D001172:Arthritis, Rheumatoid / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006680:HLA Antigens / Q000235:genetics; D006801:Humans; D050835:Interferon Regulatory Factors / Q000235:genetics; D008180:Lupus Erythematosus, Systemic / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22 / Q000235:genetics; D012307:Risk Factors; D050797:STAT4 Transcription Factor / Q000235:genetics
D006680:HLA Antigens; C431713:IRF5 protein, human; D050835:Interferon Regulatory Factors; D050797:STAT4 Transcription Factor; C494090:STAT4 protein, human; C516765:PTPN22 protein, human; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22