The HLA class II allele DQB1*0309 is associated with dilated cardiomyopathy

Previous studies have shown weak associations between human dilated cardiomyopathy (DCM) and certain human leucocyte antigen (HLA) class II polymorphisms. Using a sequence-specific primer-PCR (SSP-PCR) technology, we compared the allelic distribution in the HLA-DQ and -DR locus in a cohort of German DCM patients (n = 165) and DCM-free controls (n = 79). With the exception of HLA-DQB1*0309, we found no significant differences between the two groups, even without adjustment for multiple testing. The HLA-DQB1*0309 allele, however, was detected more frequently in DCM patients as compared to controls (28.5% versus 10.1%, p = 0.0010), leading to an odds ratio of 3.5 (95% confidence interval = 1.5–9.1). The frequency of this allele was significantly higher in DCM patients without lymphocytic infiltrates in endomyocardial biopsies as compared to patients classified histologically as inflammatory DCM (33.1% versus 14.6%, p = 0.028). There was no significant difference in the allelic HLA-DQB1*0309 distribution between DCM patients with and without viral genomes detected in the heart (24.2% versus 29.5%, p = 0.668). In summary, the frequency of the HLA-DQB1*0309 allele is overrepresented in DCM patients, suggesting that carriers of this HLA class II variant are associated with an increased risk for developing DCM. Although Bonferroni adjustment was applied, controlled studies in larger samples of DCM patients and in different ethnic populations are warranted to confirm this observation and reveal the pathophysiological mechanisms behind this association.