Patient Stratification group and Genetics and Genomics group, Biogen Idec, Cambridge, MA, USA.|Patient Stratification group and Genetics and Genomics group, Biogen Idec, Cambridge, MA, USA.|Patient Stratification group and Genetics and Genomics group, Biogen Idec, Cambridge, MA, USA.|Patient Stratification group and Genetics and Genomics group, Biogen Idec, Cambridge, MA, USA.|Patient Stratification group and Genetics and Genomics group, Biogen Idec, Cambridge, MA, USA.