The C1858T allele of the PTPN22 gene has been reported to confer risk for RA; 
but in some reports, the effect was restricted to RF- and/or 
anti-CCP-seropositive patients. Hungarian RA patients and matched controls were 
genotyped. The 1858T allele showed an increased prevalence in RA patients 
compared to controls. The 1858T allele represents a risk factor in the whole RA 
population (P = 0.001); an association was found both in RF-seropositive (P = 
0.001) and anti-CCP-seropositive patients (P = 0.001), and in subjects with the 
combination of these factors (P = 0.002). In TT homozygotes, the estimated 
susceptibility to RA was more than double (OR = 5.04) of that seen in TC 
heterozygotes (OR = 1.89); the same gene dosage effect was observed in all 
seropositive RA subgroups. Our data show that the Hungarian RA patients belong 
to the populations in which the 1858T allele represents a susceptibility factor 
both in the RF- and/or anti-CCP-seropositive subjects, and the association 
exhibit a gene dosage dependency.