Paradigmatic de novo GRIN1 variants recapitulate pathophysiological mechanisms underlying GRIN1-related disorder clinical spectrum

Background: GRIN-related disorders (GRD), the so-called grinpathies, is a group of rare encephalopathies caused by mutations affecting GRIN genes (mostly GRIN1, GRIN2A and GRIN2B genes), which encode for the GluN subunit of the N-methyl D-aspartate (NMDA) type ionotropic glutamate receptors. A growing number of functional studies indicate that GRIN-encoded GluN1 subunit disturbances can be dichotomically classified into gain- and loss-of-function, although intermediate complex scenarios are often present. Methods: In this study, we aimed to delineate the structural and functional alterations of GRIN1 disease-associated variants, and their correlations with clinical symptoms in a Spanish cohort of 15 paediatric encephalopathy patients harbouring these variants. Results: Patients harbouring GRIN1 disease-associated variants have been clinically deeplyphenotyped. Further, using computational and in vitro approaches, we identified different critical checkpoints affecting GluN1 biogenesis (protein stability, subunit assembly and surface trafficking) and/or NMDAR biophysical properties, and their association with GRD clinical symptoms. Conclusions: Our findings show a strong correlation between GRIN1 variants-associated structural and functional outcomes. This structural-functional stratification provides relevant insights of genotypephenotype association, contributing to future precision medicine of GRIN1-related encephalo

Kleine-Levin syndrome: Differential diagnosis in recurrent encephalitic syndromes in adolescence

Introducción. El síndrome de Kleine-Levin es una enfermedad rara de causa desconocida que se caracteriza por episodios recurrentes autolimitados de hipersomnia acompañados de alteración cognitiva y conductual. Entre los episodios, los pacientes tienen un patrón de sueño y cognitivo normal. Casos clínicos. Se presentan tres pacientes de 14 años, dos chicos y una chica. Comenzaron tras un desencadenante (vacuna, una infección respiratoria por influenza B; en el caso de la chica, coincidían con la menstruación). En el episodio agudo mostraban tendencia al sueño y en vigilia destacaba bradipsiquia, inquietud motora y gran labilidad emocional, con tendencia al llanto y necesidad de la presencia de los familiares. Presentaron una duración aproximada de 10-15 días y periodicidad mensual, y se mostraron asintomáticos entre los episodios. Los tres pacientes fueron valorados por pediatras, diagnosticados y tratados de encefalitis autoinmune. Sólo uno cumplía la tríada típica de hipersomnia, hiperfagia e hipersexualidad, pero ninguno de los tres datos se había recogido en la historia clínica inicial y la familia sólo lo refería tras una anamnesis dirigida. Conclusiones. En el síndrome de Kleine-Levin, los síntomas neurológicos durante el cuadro agudo son aún más frecuentes que los psiquiátricos. La tendencia al sueño y el hecho de que durante la vigilia no estén asintomáticos y se muestren lentos, apáticos, lábiles e irascibles, sitúa en primer lugar la sospecha de síndrome encefalítico. Debemos tener presente esta entidad en encefalitis recurrentes de etiología no filiadaIntroduction. The Kleine-Levin syndrome is a rare disease of unknown origin characterized by recurrent and self-limited episodes of hypersomnia that are also accompanied by a cognitive and behavioral dysfunction. Patients present normal sleeping and behavior patterns between episodes. Case reports. We present three patients who are 14 years old: two boys and one girl. They started having the episodes after a predisposing factor (vaccine, influenza B and menstruation). During the episode they presented hypersomnolence and while wakefulness they were bradipsychic, in motor restlessness and with emotional liability. They also presented a tendency towards crying and claimed the presence of relatives constantly. The episodes lasted between 10 and 15 days and they appeared monthly, being asymptomatic between episodes. All three patients were attended initially by pediatricians, diagnosed and treated as autoimmune encephalitis. Only one of our cases had the three typical symptoms of hypersomnia, hyperfagia and hypersexuality. However, none of the three had been asked initially and the family only referred to it after the directed anamnesis. Conclusions. The Kleine-Levin syndrome presents neurologic symptoms initially more frequently than psychiatric ones. Hypersomnia and behavioural disturbances during wakefulness, bradypsychia, apatheia and emotional liability make us suspect that it could be an encephalitis process. We should be aware of this entity if we face a patient with recurrent encephalitis of unknown origi