It relates to a method for determining the efficiency of the tratamientyo IFN - B to a subject with Multiple Sclerosis comprising: (i) to administer a dose of interferon beta to the subject (ii) obtaining a Biological sample from the subject in a Time less than 12 hours after the Administration of Interfer On.The Blood sample is from which RNA was isolated (iii) determine the level of expression of at least one Gene regulated by interferon (IRG) and \/ or its Variant (iv) administering to the subject a therapeutically effective amount of at least one Agent as natalizumab Plus interferon beta if EXP At least a resion IRG and \/ or its Variant increases or decreases in comparison with a control.This method allows to observe the increase or decrease of the expression of the IRG and \/ or its variants which indicates whether the subject will respond poorly to treatment with interferon beta.SE REFIERE A UN METODO PARA DETERMINAR LA EFICIENCIA DEL TRATAMIENTYO CON IFN-B A UN SUJETO CON ESCLEROSIS MULTIPLE QUE COMPRENDE: (i) ADMINISTRAR UNA DOSIS DE INTERFERON BETA AL SUJETO (ii) OBTENER UNA MUESTRA BIOLOGICA DEL SUJETO EN UN TIEMPO MENOR DE 12 HORAS DESDE LA ADMINISTRACION DEL INTERFERON. LA MUESTRA ES SANGRE DE LA CUAL SE AISLA EL ARN (iii) DETERMINAR EL NIVEL DE EXPRESION DE AL MENOS UN GEN REGULADO POR INTERFERON (IRG) Y/O SU VARIANTE (iv) ADMINISTRAR AL SUJETO UNA CANTIDAD TERAPEUTICAMENTE EFECTIVA DE AL MENOS UN AGENTE TAL COMO NATALIZUMAB, ADEMAS DE INTERFERON BETA SI LA EXPRESION DE AL MENOS UN IRG Y/O SU VARIANTE AUMENTA O DISMINUYE EN COMPARACION CON UN CONTROL. DICHO METODO PERMITE OBSERVAR EL AUMENTO O DISMINUCION DE LA EXPRESION DEL IRG Y/O SUS VARIANTES LO CUAL INDICA SI EL SUJETO RESPONDERA MAL AL TRATAMIENTO CON INTERFERON BETA.
