Genetic variation in the IL7RA/IL7 pathway increases multiple sclerosis susceptibility Rebecca L. ZuvichJacob L. McCauleyJorge R. OksenbergStephen J. Sawcer • Philip L. De JagerInternational Multiple Sclerosis Genetics ConsortiumCristin Aubin • Anne H. CrossLaura PiccioNeelum T. AggarwalDenis EvansDavid A. Hafler • Alastair CompstonStephen L. HauserMargaret A. Pericak-VanceJonathan L. Haines

Multiple sclerosis (MS) is characterized as an autoimmune demyelinating disease. Numerous family studies have confirmed a strong genetic component underlying its etiology. After several decades of frustrating research, the advent and application of affordable geno- typing of dense SNP maps in large data sets has ushered in a new era in which rapid progress is being made in our understanding of the genetics underlying many complex traits. For MS, one of the first discoveries to emerge in this new era was the association with rs6897932(T244I) in the interleukin-7 receptor alpha chain (IL7RA) gene (Gregory