RESUMEN
OBJECTIVE: During the evolution of the human genome, a number of retroviral integrations have occurred creating a group of human endogenous retroviruses (HERVs). As of now several studies have pointed to the association of HERVs with certain autoimmune diseases such as RA, SLE, multiple sclerosis (MS) and SS as well as various neoplasms. In this study, we investigated the prevalence of HERV-K113 in patients with RA, SLE and in healthy subjects in the Polish population. METHODS: Genomic DNA samples from 155 RA patients, 139 SLE patients and 261 newborns (as controls) were tested for the presence of the HERV-K113 allele using PCR. Each individual's DNA was genotyped for null, homozygous or heterozygous insertion of HERV-K113. RESULTS: Our data revealed statistically significant differences in the insertion frequencies of HERV-K113 between the groups of RA and SLE patients vs healthy controls (provirus DNA was found in 14.19, 15.11 and 8.05% of individuals, respectively). No homozygous individuals for the K113 allele were found in each of the groups. There was no evidence for HERV-K113 association with clinical features in either group. CONCLUSION: Our study-the first such performed for the Polish population-provides a consistent observation with previous reports on the genetic association of HERV-K113 integrations in autoimmune disorders. Here, we found that the prevalence of insertionally polymorphic HERV-K113 was significantly increased in Polish patients with SLE and RA.