Toll-like receptor-9 in Spanish multiple sclerosis patients: an association with the gender.

BACKGROUND AND PURPOSE: Toll-like receptor-9 (TLR9) is a potent inducer of innate immune system triggered by infection with viruses, some of them previously related to multiple sclerosis (MS). The aim of this study was to analyze the possible association of two TLR9 single nucleotide polymorphisms (SNPs; rs352162 and rs187084) with susceptibility to MS. METHODS: Two independent cohorts of MS patients and controls were included: 574 clinically definite relapsing-remitting MS patients (367 females) and 807 healthy controls (418 females) for the first cohort; and 366 relapsing-remitting MS patients (238 females) and 224 healthy controls (160 females) for the second cohort. Genotyping was performed by TaqMan assays. RESULTS: The AT haplotype was found to be significantly higher in women than in men (P = 0.013 and P = 0.044). CONCLUSIONS: Here two possible genetic markers are proposed that could be also associated with the differences observed in the clinical course of MS in both genders. Further studies with larger cohorts should be performed to confirm these results.

MHC2TA rs4774C and HHV-6A active replication in multiple sclerosis patients.

BACKGROUND AND PURPOSE: In a previous report, a strong gene-environment interaction between human herpesvirus 6A (HHV6A) active replication and MHC2TA rs4774C was demonstrated. The objectives of this study were: (i) to reappraise the association that was found in the previous study; (ii) to evaluate if MS patients with minor allele C and HHV-6A active infection had different clinical behavior; and (iii) to analyze the possible association of MHC2TA rs4774C with Epstein-Barr virus (EBV). METHODS: A total of 149 MS patients were analyzed both at the MHC2TA locus and by HHV-6A status in serum. We studied a G/C polymorphism (rs4774) by a TaqMan Assay-on-Demand. HHV-6A genomes in serum were evaluated by quantitative PCR. A control group of 562 healthy Spanish individuals was included for comparative purposes in the genetic analyses. A battery of clinical data was collected for all the MS patients included in the study. RESULTS: (i) MHC2TA/HHV-6A interaction: we found the same strong association of the rs4774C allele with HHV-6A active replication than in the previous study (P = 0.0001). (ii) CLINICAL DATA: the two main statistical significant differences for MS patients with HHV-6A active infection and minor allele C were: (a) a significant number of them were not free of progression (EDSS = 0) 2 years after the diagnosis (P = 0.01); (b) only a third of them responded to interferon beta treatment (P = 0.05). CONCLUSIONS: This study has verified previous results about the strong gene-environment interaction between HHV6A active replication and MHC2TA rs4774C. Furthermore, a different clinical behavior for MS patients with HHV-6A active infection and minor allele C was found.