A number of studies reported associations of HLA-DRB1, TNFalpha (TNF) promoter 
and TNF receptor II (TNFR2, TNFRSF1B) polymorphisms with systemic lupus 
erythematosus (SLE), however, the results have often been inconsistent. Such 
lack of consistency could partly derive from the population admixture involved 
in the case-control study. To avoid such a problem, polymorphisms in these genes 
were analyzed using transmission disequilibrium test (TDT) in Caucasian SLE 
families. Ninety-one Caucasian SLE family samples recruited in southern 
California were analyzed for the association with HLA-DRB1, TNF promoter 
positions at -1031, -863, -857 and -308, and TNFR2-196M/R polymorphisms. 
Significant transmission was observed for HLA-DRB1*1501, but not for 
HLA-DRB1*0301, nor for TNF haplotype that codes for -308A. Interestingly, TNF 
haplotype coding for -1031C, -863A, -857C showed a tendency of preferential 
nontransmission in the patients without lupus nephritis and in those with malar 
rash. No transmission distortion was observed for TNFR2-196R allele. These 
findings confirmed the association of HLA-DRB1*1501, but did not replicate that 
of the HLA-DRB1*0301, TNFA-308A and TNFR2-196R with SLE in this population. In 
addition, a possible disease-protective role for TNF haplotype coding for 
-1031C, -863A, -857C was suggested.