Systemic lupus erythematosus and rheumatoid arthritis

16. Paper III: The R620W C/T polymorphism of the gene 
PTPN22
 is 
associated with SLE independently of the association of PDCD1. 
In a collaborative study spanning Sweden, association of a polymorphism, 
PTPN22
1858C/T, or R620W, within the 
PTPN22
gene with SLE susceptibility 
was identified (Table 12). The strongest association with SLE came from the 
northern Swedish material. The risk allele of the 1858C/T polymorphism has 
been shown to have a higher frequency in northern European countries 
compared with southern European countries.
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Table 12.
Allelic associations of Swedish SLE cases and controls