NOS2A as a candidate gene in Relapsing-Remitting Multiple Sclerosis: a haplotype study using selected subsets of single nucleotide polymorphisms.

As with other autoimmune diseases, susceptibility to multiple sclerosis (MS) is believed to result from the complex interaction of a number of genes, each with modest effect. Several genome-wide screens have implicated the nitric oxide synthase 2A gene (NOS2A), which encodes the inducible form of nitric oxide synthase, as being potentially associated with MS. To determine whether genetic variants within this gene may constitute a risk factor for causing MS, we investigated 13 single nucleotide polymorphisms in the NOS2A gene, in a case-control group of 214 Italian patients with MS and 121 controls. All these single nucleotide polymorphisms (SNPs) were analyzed using the SNPlex(TM) Genotyping System (Applied Biosystems). Data were analyzed using Genemapper 4.0 and Haploview 4.1. No significant association between cases and controls (P>0.05) was observed for the alleles of the SNPs. Defining the haplotype blocks also failed to detect any associated haplotypes. Our results suggest that polymorphic variation within the NOS2A gene does not influence the susceptibility to MS in patients of Italian origin.