Background: Rheumatic heart disease (RHD) is an autoimmune sequel of group A streptococcal infection that has been associated with the presence of some major histocompatibility complex (MHC) genes. Thus, the aim of the present study was to investigate the role of class II alleles in the genetic susceptibility to RHD in Mexican patients and establish the relationship of these alleles with the pattern of valve damage.
Methods: HLA-DR, -DQA1 and -DQB1 allele frequencies were determined by PCR-SSO reverse dot blot and PCR-SSP in 98 Mexican Mestizo patients with RHD and 99 healthy controls. Patients were divided into mitral valve damage (n=46), multivalvular lesion (n=49) and aortic damage (n=3).
Results: RHD patients presented an HLA-DR16 increased frequency (pC=0.009, OR=3.9) and a decreased HLA-DR11 frequency (pC=0.018) when compared to healthy controls. HLA-DR16 subtyping showed that DRB1*1602 was the DR16 allele increased in patients (pC=0.007, OR=5.3). Haplotype analysis showed increased frequency of DR16-DQA1*0501-DQB1*0301 in RHD patients when compared to healthy controls (pC=0.011). HLA-DR16 frequency remained significantly increased on patients with multivalvular lesion (pC=0.004, OR=4.8).
Conclusions: Our data suggest an important participation of Amerindian autochthonous HLA-DR16 (DRB1*1602) allele and DR16-DQA1*0501-DQB1*0301 haplotype as markers for RHD genetic susceptibility in the Mexican Mestizo population. HLA-DR16 allele could also play an important role in determining the pattern of valve damage on these patients.