Lack of association of the PTPN22 gene polymorphism R620W with systemic sclerosis.
OBJECTIVE
It has recently been reported that some autoimmune diseases seem to be associated with a functional polymorphism in PTPN22, a gene which encodes a phosphatase known to be important in T-cell signaling. The aim of our study was to check for the prevalence of the PTPN22 R620W polymorphism in patients with systemic sclerosis.


METHODS
DNA samples from 54 systemic sclerosis patients and 55 healthy controls were obtained from peripheral blood and genotyping was performed by means of a restriction fragment length polymorphism analysis of PCR products (RFLP-PCR).


RESULTS
Allele frequency for the T allele was slightly higher in the patients group (0.074 versus 0.055). Eight out of the 54 systemic sclerosis patients (14.8 %) were heterozygous for this single nucleotide polymorphism whereas the CT genotype was found in 6 out of the 55 controls (10.9%). Nevertheless, the difference did not reach statistical significance (p = 0.542). Neither certain antibodies linked to systemic sclerosis (anti-centromere and anti-topoisomerase I antibodies) nor any particular clinical involvement were associated with the polymorphism.


CONCLUSIONS
This particular single nucleotide polymorphism of PTPN22 does not seem to be associated with systemic sclerosis.
Balada
E
E
Research Unit in Systemic Autoimmune Diseases, Vall d'Hebron Research Institute, Hospital Vall d'Hebron, Barcelona, Spain. ebalada@ir.vhebron.net
Simeón-Aznar
C P
CP
Serrano-Acedo
S
S
Martínez-Lostao
L
L
Selva-O'Callaghan
A
A
Fonollosa-Pla
V
V
Vilardell-Tarrés
M
M
D000974:Antibodies, Antinuclear / Q000097:blood; D002503:Centromere / Q000276:immunology; D004264:DNA Topoisomerases, Type I / Q000276:immunology; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006801:Humans; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D012595:Scleroderma, Systemic / Q000235:genetics* / Q000276:immunology / Q000473:pathology
D000974:Antibodies, Antinuclear; C516765:PTPN22 protein, human; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22; D017027:Protein Tyrosine Phosphatases; D004264:DNA Topoisomerases, Type I