Cardiovascular disease (CVD) is more prevalent and more likely to lead to death in patients with rheumatoid arthritis (RA). Single nucleotide polymorphisms of the genes for lymphotoxin-A (LT-A) and its regulatory protein galectin-2 (LGALS2) have been implicated as genetic risk factors for acute cardiovascular events in the general population: we hypothesised that their risk alleles/genotypes (a) may be more frequent among patients with RA compared with non-RA controls (thus explaining some of the increased CVD in RA), and (b) may be more frequent among patients with RA with prevalent CVD compared with patients with RA without CVD.
Genomic DNA samples were collected from 388 patients with RA and 399 local population controls without RA. LT-A gene intron 1 252A>G and LGALS2 intron 1 3279C>T single nucleotide polymorphisms were identified using real-time polymerase chain reaction and melting curve analysis.
LT-A 252GG homozygotes were significantly more prevalent among patients with RA compared with controls (19.8% vs 11.8%, p = 0.002; OR(GG/GA,AA) = 1.85, 95% CI 1.25 to 2.75, p = 0.002). Patients with RA possessing LT-A 252 GG were significantly more likely to have had a myocardial infarction compared with those with LT-A 252 AA or GA (13% vs 5.5%, p = 0.02; adjusted OR(GG/GA,AA) = 3.03, 95% CI 1.2 to 7.68, p = 0.002). The frequency of LGALS2 polymorphisms was similar between RA and controls and was not associated with CVD among patients with RA.
The LT-A 252GG genotype occurs more frequently among patients with RA than the general population. In RA, this genotype appears to associate with increased likelihood of suffering an myocardial infarction.