Valine/valine genotype at position 247 of the β2‐glycoprotein I gene in Mexican patients with primary antiphospholipid syndrome: Association with anti–β2‐glycoprotein I antibodies

Objective To determine the polymorphism at position 247 of the β2‐glycoprotein I (β2GPI) gene in Mexican patients with antiphospholipid syndrome (APS) and to compare these data in patients with or without antibodies to β2GPI and with the clinical manifestations of APS. Methods We studied 39 patients with primary APS and compared them with 106 clinically healthy subjects. Polymorphism was determined by polymerase chain reaction–restriction fragment length polymorphism. The presence of “true” anticardiolipin (aCL) antibodies, β2GPI‐dependent aCL antibodies (IgG and IgM), and phospholipid‐free anti‐β2GPI antibodies (IgG isotype) were detected by enzyme‐linked immunosorbent assay (ELISA) utilizing nonirradiated ELISA plates. Clinical manifestations associated with antiphospholipid antibodies were also evaluated. Results We found no significant differences in the genotype expression between the control group and the primary APS patients (13% with VV, 52% with VL, and 35% with LL versus 23% with VV, 51% with VL, and 26% with LL, respectively). In contrast, anti‐β2GPI–positive patients had significantly higher frequencies of the VV genotype and V allele expression than the control subjects and the anti‐β2GPI–negative patients. These genotype and allele frequencies were also significantly higher in patients with arterial thrombosis than in patients without it. Anti‐β2GPI–negative patients without arterial thrombosis did not express the VV genotype. We found no differences in the Val/Leu247 polymorphism of the β2GPI gene in primary APS patients with or without “true” aCL antibodies or in primary APS patients with or without β2GPI‐dependent aCL antibodies. Conclusion Our results suggest that the VV genotype at position 247 of the β2GPI gene may play a role in the generation of anti‐β2GPI antibodies and perhaps in the expression of arterial thrombosis in primary APS.