title: Polymorphisms in the genes coding for iron binding and transporting proteins are associated with disability, severity, and early progression in multiple sclerosis.
abstract: BACKGROUND
  Iron involvement/imbalance is strongly suspected in multiple sclerosis (MS) etiopathogenesis, but its role is quite debated. Iron deposits encircle the veins in brain MS lesions, increasing local metal concentrations in brain parenchyma as documented by magnetic resonance imaging and histochemical studies. Conversely, systemic iron overload is not always observed. We explored the role of common single nucleotide polymorphisms (SNPs) in the main iron homeostasis genes in MS patients.
  
  
  METHODS
  By the pyrosequencing technique, we investigated 414 MS cases [Relapsing-remitting (RR), n=273; Progressive, n=141, of which: Secondary (SP), n=103 and Primary (PP), n=38], and 414 matched healthy controls. Five SNPs in 4 genes were assessed: hemochromatosis (HFE: C282Y, H63D), ferroportin (FPN1: -8CG), hepcidin (HEPC: -582AG), and transferrin (TF: P570S).
  
  
  RESULTS
  The FPN1-8GG genotype was overrepresented in the whole MS population (OR=4.38; 95%CI, 1.89-10.1; P<0.0001) and a similar risk was found among patients with progressive forms. Conversely, the HEPC -582GG genotype was overrepresented only in progressive forms (OR=2.53; 95%CI, 1.34-4.78; P=0.006) so that SP and PP versus RR yielded significant outputs (P=0.009). For almost all SNPs, MS disability score (EDSS), severity score (MSSS), as well as progression index (PI) showed a significant increase when comparing homozygotes versus individuals carrying other genotypes: HEPC -582GG (EDSS, 4.24±2.87 vs 2.78±2.1; P=0.003; MSSS, 5.6±3.06 vs 3.79±2.6; P=0.001); FPN1-8GG (PI, 1.11±2.01 vs 0.6±1.31; P=0.01; MSSS, 5.08±2.98 vs 3.85±2.8; P=0.01); HFE 63DD (PI, 1.63±2.6 vs 0.6±0.86; P=0.009). Finally, HEPC -582G-carriers had a significantly higher chance to switch into the progressive form (HR=3.55; 1.83-6.84; log-rank P=0.00006).
  
  
  CONCLUSIONS
  Polymorphisms in the genes coding for iron binding and transporting proteins, in the presence of local iron overload, might be responsible for suboptimal iron handling. This might account for the significant variability peculiar to MS phenotypes, particularly affecting MS risk and progression paving the way for personalized pharmacogenetic applications in the clinical practice.
authors.affiliation: Department of Biomedical Sciences & Advanced Therapies, Hematology Unit-Center Hemostasis & Thrombosis, University of Ferrara, Ferrara, Italy. d.gemmati@unife.it
authors.forename: Donato
authors.initials: D
authors.lastname: Gemmati
authors.forename: Giulia
authors.initials: G
authors.lastname: Zeri
authors.forename: Elisa
authors.initials: E
authors.lastname: Orioli
authors.forename: Francesca E
authors.initials: FE
authors.lastname: De Gaetano
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Salvi
authors.forename: Ilaria
authors.initials: I
authors.lastname: Bartolomei
authors.forename: Sandra
authors.initials: S
authors.lastname: D'Alfonso
authors.forename: Claudia
authors.initials: C
authors.lastname: Dall'osso
authors.forename: Maurizio A
authors.initials: MA
authors.lastname: Leone
authors.forename: Ajay V
authors.initials: AV
authors.lastname: Singh
authors.forename: Rosanna
authors.initials: R
authors.lastname: Asselta
authors.forename: Paolo
authors.initials: P
authors.lastname: Zamboni
mesh_terms: D000328:Adult; D023181:Antimicrobial Cationic Peptides / Q000235:genetics; D027682:Cation Transport Proteins / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D006432:Hemochromatosis / Q000235:genetics; D000071020:Hemochromatosis Protein; D064451:Hepcidins; D015395:Histocompatibility Antigens Class I / Q000235:genetics; D006801:Humans; D033862:Iron-Binding Proteins / Q000235:genetics*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000235:genetics*; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D012720:Severity of Illness Index; D014168:Transferrin; D000098742:Ferroportin
chemical_list: D023181:Antimicrobial Cationic Peptides; D027682:Cation Transport Proteins; C578702:HAMP protein, human; C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D064451:Hepcidins; D015395:Histocompatibility Antigens Class I; D033862:Iron-Binding Proteins; D008565:Membrane Proteins; D014168:Transferrin; D000098742:Ferroportin