@article{Cocco2012, abstract = {Introduction: Genetic predisposition to multiple sclerosis (MS) in Sardinia (Italy) has been associated with five DRB1*-DQB1* haplotypes of the human leukocyte antigen (HLA). Given the complexity of these associations, an in-depth re-analysis was performed with the specific aims of confirming the haplotype associations; establishing the independence of the associated haplotypes; and assessing patients’ genotypic risk of developing MS. Methods and Results: A transmission disequilibrium test (TDT) of the DRB1*-DQB1* haplotypes in 943 trio families, confirmed a higher than expected transmission rate (over-transmission) of the *13:03-*03:01 (OR = 2.9, P = 7.661023), *04:05-*03:01 (OR = 2.4, P = 4.461026) and *03:01-*02:01 (OR = 2.1, P = 1.0610215) haplotype. In contrast, the *16:01-*05:02 (OR = 0.5, P = 5.4610211) and the *15:02-*06:01 (OR = 0.3, P = 1.561023) haplotypes exhibited a lower than expected transmission rate (under-transmission). The independence of the transmission of each positively and negatively associated haplotype was confirmed relative to all positively associated haplotypes, and to the negatively associated *16:01-*05:02 haplotype. In patients, carriage of two predisposing haplotypes, or of protective haplotypes, respectively increased or decreased the patient’s risk of developing MS. The risk of MS followed a multiplicative model of genotypes, which was, in order of decreasing ORs: *04:05-*0301/*03:01-*02:01 (OR = 4.5); *03:01-*02:01/*03:01-*02:01 (OR = 4.1); and the *16:01- *05:02/*16:01-*0502 (OR = 0.2) genotypes. Analysis of DRB1 and DQB1 protein chain residues showed that the Val/Gly residue at position 86 of the DRB1 chain was the only difference between the protective *16:01- *15:02 alleles and the predisposing *15:01 one. Similarly, the Ala/Val residue at position 38 of the DQB1 chain differentiated the positively associated *06:02 allele and the negatively associated *05:02, *06:01 alleles. Conclusions: These findings show that the association of specific, independent DRB1*-DQB1* haplotypes confers susceptibility or resistance to MS in the MS-prone Sardinian population. The data also supports a functional role for specific residues of the DRB1 and DQB1 proteins in predisposing patients to MS.}, author = {Cocco, Eleonora and Sardu, Claudia and Pieroni, Enrico and Valentini, Maria and Murru, Raffaele and Costa, Gianna and Tranquilli, Stefania and Frau, Jessica and Coghe, Giancarlo and Carboni, Nicola and Floris, Matteo and Contu, Paolo and Marrosu, Maria Giovanna}, doi = {10.1371/journal.pone.0033972}, journal = {PLoS ONE}, month = {apr}, pages = {e33972}, title = {HLA-DRB1-DQB1 Haplotypes Confer Susceptibility and Resistance to Multiple Sclerosis in Sardinia}, url = {https://doi.org/10.1371/journal.pone.0033972}, volume = {7}, year = {2012} }