PURPOSE: To investigate whether polymorphic differences can be identified between Multiple sclerosis (MS) patients treated by fingolimod who had liver enzymes elevation compared to those who do not.~OBJECTIVE: To determine whether elevated liver enzyme tests (ALT, AST, GGT or bilirubinemia above the upper limit of normal) in MS patients treated with fingolimod is associated with genetic polymorphisms.~METHOD OF RECRUITMENT:~Patients will be identified through a clinic database and chart reviews. A phone call will be made to determine interest. Upon a follow-up neurological consultation, consent into study will be sought.~PROCEDURES:~Blood samples will be collected for genetic analyses, fingolimod and fingolimod-phosphate quantification and a questionnaire will be administered
To investigate whether polymorphic differences can be identified between Multiple Sclerosis patients developing elevated liver enzymes (defined as ALT, AST, GGT or bilirubinemia levels five above the upper normal limit on at least one) compared to those not developing elevated liver enzymes after exposure to fingolimod for multiple sclerosis.