Gm allogenotype distribution and lack of HLA-DR, Gm interaction in SLE and CREST/PSS.
The distribution of Gm allogenotypes (Gm allotypes identified by IgCH restriction fragment length polymorphism (RFLP) analysis) was compared in 66 systemic lupus erythematosus (SLE) patients, 38 CREST/PSS group (P less than 0.05) but not in the SLE group. HLA-DR5 is significantly increased in frequency in this series of CREST/PSS patients compared to controls (P less than 0.001), and log linear regression analysis showed that although both DR5 and Gm homozygosity were significant factors determining disease susceptibility, there was no evidence of an interactive effect between these two groups of genes increasing the predisposition to CREST/PSS.