A method for predictively diagnosing the likelihood of a patient suffering from SMEI comprising: (i) sequencing a patient's SC1NA gene in order to detect a mutation in the patient's SCN1A gene, included in a regulatory region of the gene, in a sample of the patient； (ii) determine if the mutation has been previously detected, or not, in the SCN1A gene of the subjects and it is known that it is associated with the SMEI, or has not been previously associated with the SMEI, where, when the identified mutation has not Having previously been associated with SMEI, the patient's parents or relatives also undergo analysis to determine if the patient's mutation has arisen de novo. where said predictive diagnosis of SMEI risk is as follows: (a) if the mutation has been previously associated with SMEI, then a high probability of SMEI risk is anticipated； (b) if the mutation is known and has not been previously associated with SMEI, then a low probability of SMEI risk is anticipated； and (c) if the mutation has not been previously identified and has been shown to have arisen de novo, there is a high probability of SMEI risk and an even greater risk if the mutation is identified as a truncation mutation.Un método para diagnosticar predictivamente la probabilidad de que un paciente sufra de SMEI que comprende: (i) secuenciar el gen SC1NA de un paciente con el fin de detectar una mutación en el gen SCN1A del paciente, incluida en una región reguladora del gen, en una muestra del paciente； (ii) determinar si la mutación ha sido detectada previamente, o no, en el gen SCN1A de los sujetos y se sabe que está asociada a la SMEI, o no ha sido asociada previamente a la SMEI, donde, cuando la mutación identificada no ha sido asociada previamente a la SMEI, los padres o familiares del paciente también se someten a análisis para determinar si la mutación del paciente ha surgido de novo. donde dicho diagnóstico predictivo de riesgo de SMEI es de la manera siguiente: (a) si la mutación ha sid
