Genotyping of Italian Patients with Behçet Syndrome Identified Two Novel ERAP1 Polymorphisms Using Sequencing-Based Approach

The endoplasmic reticulum aminopeptidase protein 1 gene (ERAP1) is related to several human diseases, including Behçet syndrome (BS), a multisystemic disorder with unknown etiology. ERAP1 is involved in immune response and its role can be influenced by gene single nucleotide variations (SNVs). We genotyped the ERAP1 whole structure in 50 consecutive BS patients and 50 ethnically-matched healthy controls using both bioinformatics and molecular methodologies. We identified two novel heterozygous missense SNVs of ERAP1 exon3 responsible for the p.Glu183Val and p.Phe199Ser changes. The first variation was recognized in 7/50 (14%) BS patients and involved the substrate binding site (p.Glu183) required for the anchorage of the peptide N-terminal group. The SNV was predicted to be a damaging variation, as well as the p.Phe199Ser substitution (PolyPhen-2 and SIFT on line software). 3D protein structure prediction showed a change in energy score when the wild-type and the variant states were compared, probably influencing the substrate binding and the protein folding. The first variation was associated to a more stable protein chain, while the second polymorphism was related to a less stable protein chain. Our data need to be tested in larger genetic studies.