title: Parent-of-origin of HLA-DRB1*1501 and age of onset of multiple sclerosis.
abstract: Multiple sclerosis (MS) is a complex neurological trait. Allelic variation in the MHC class II region exerts the single strongest effect on MS genetic risk. The clinical onset of the disease is extremely variable, and can range from the first to the ninth decade of life. Epidemiological studies have suggested a modest genetic component to the age of onset (AO) of MS. Previous studies have shown that HLA-DRB1*1501 may be associated with a younger AO. Here, we sought to uncover any effect of HLA-DRB1*1501 on the AO of MS in a large Canadian cohort. A total of 1816 MS patients were genotyped for HLA-DRB1. Patients carrying HLA-DRB1*1501 were shown to have a small, but significantly lower, AO than patients without the allele (P=0.03). HLA-DRB1*1501 was also shown to reduce the mean AO in both progressive and relapsing forms of the disease. An investigation of parent-of-origin effects indicated that the lower AO for HLA-DRB1*1501 patients arises from maternally transmitted HLA-DRB1*1501 haplotypes (maternal HLA-DRB1*1501 mean AO=28.4 years, paternal=30.3 years; P=0.009). HLA-DRB1*1501 exerts a modest, but significant effect on the AO of all forms of MS. Parent-of-origin effects at the MHC are further implicated in MS disease pathogenesis.
authors.affiliation: Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Sreeram V
authors.initials: SV
authors.lastname: Ramagopalan
authors.forename: Jake K
authors.initials: JK
authors.lastname: Byrnes
authors.forename: David A
authors.initials: DA
authors.lastname: Dyment
authors.forename: Colleen
authors.initials: C
authors.lastname: Guimond
authors.forename: Lahiru
authors.initials: L
authors.lastname: Handunnetthi
authors.forename: Giulio
authors.initials: G
authors.lastname: Disanto
authors.forename: Irene M
authors.initials: IM
authors.lastname: Yee
authors.forename: George C
authors.initials: GC
authors.lastname: Ebers
authors.forename: A Dessa
authors.initials: AD
authors.lastname: Sadovnick
mesh_terms: D000328:Adult; D017668:Age of Onset; D000483:Alleles; D002170:Canada; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006684:HLA-DR Antigens / Q000235:genetics* / Q000276:immunology; D059811:HLA-DRB1 Chains; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000235:genetics*; D010290:Parents; D010641:Phenotype; D012307:Risk Factors
chemical_list: D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; C489631:HLA-DRB1*15:01 antigen