Disparate treatment outcomes according to presence of pathogenic mutations in West syndrome

Objective It has been known that West syndrome (WS) patients with an unknown etiology have better clinical outcomes than patients with an identified etiology of any kind. However, after the exponential discovery of genes with mutations responsible for developmental and epileptic encephalopathy (DEE), a significant proportion of patients with a previously unknown etiology have been reclassified as having a genetic etiology, requiring reinvestigation of this concept. Therefore, this study investigated clinical outcomes of WS patients with genetic and unknown etiologies. Methods Patients diagnosed with WS without structural or metabolic abnormalities were included in this study. The DEE gene panel, comprising 172 genes, was performed for all patients. All patients were treated using the same treatment protocol for vigabatrin and high‐dose prednisolone add‐on therapy. Favorable responders were defined as patients who were seizure‐free and whose electroencephalogram showed Burden of Amplitudes and Epileptiform Discharges scores of 2 or less. Results Of the 58 patients included in the study, 17 (29.3%) patients had an identified genetic etiology. There was no significant difference in rates of favorable response at 1 and 3 months after treatment, but significantly higher proportions of patients exhibited favorable responses among those with an unknown etiology at long‐term follow‐up (41.2% vs. 78.0%, p = .006 at 6 months; 29.4% vs. 65.9%, p = .011 at 1 year; 23.5 vs. 65.9%, p = .003 at 2 years). Moreover, the mental, psychomotor, and social age quotients of the patients with an identified genetic etiology were reduced to a significantly greater degree since diagnosis compared with those of the patients with an unknown etiology. Significance WS patients with genetic and unknown etiologies did not initially exhibit significantly different response rates to the vigabatrin and high‐dose prednisolone add‐on treatment. However, patients with a genetic etiology exhibited significantly higher relapse rates and significantly poorer long‐term responses.