Heterogeneidad clínica y molecular en los trastornos asociados con CDKL5 / Clinical and molecular heterogeneity in CDLK5 disorders

Resumen Introducción: El síndrome por deficiencia de CDKL5 es originado por variantes patogénicas en el gen CDKL5, con un espectro clínico variable que va desde pacientes con características del trastorno del espectro autista hasta epilepsia de inicio temprano y refractaria al tratamiento. Inicialmente fue considerado como una forma atípica de síndrome de Rett. Casos clínicos: Presentamos tres pacientes no relacionadas, evaluadas por retraso global del desarrollo y epilepsia refractaria. Los tres casos eran hemicigotos a una variante patógena de CDKL5. En una paciente se realizó panel de 306 genes asociados con epilepsia; en las otras dos se realizó microarreglo genómico comparativo. Las características clínicas y los hallazgos en el electroencefalograma y la resonancia magnética cerebral se han descrito clásicamente en el espectro de manifestaciones de este síndrome. Conclusiones: El síndrome por deficiencia de CDKL5 representa un reto para los médicos, ya que en muchos casos las manifestaciones clínicas y los estudios electroencefalográficos y de neuroimagen pueden ser inespecíficos. Debe sospecharse este síndrome ante la presencia de retraso global del desarrollo, fenotipo conductual autista y epilepsia, asociado o no con dismorfias. Dada la similitud entre diversas encefalopatías epilépticas, se deben solicitar paneles multigénicos que incluyan la secuenciación y el análisis de duplicación/deleción en los que se contemple este gen y sus posibles diagnósticos diferenciales, aunque sin olvidar la utilidad de las técnicas genómicas en casos poco claros.

Abstract Background: CDKL5 deficiency syndrome is caused by pathogenic variants in the CDKL5 gene, with a variable clinical spectrum ranging from patients with characteristics of autism spectrum disorder to early-onset epilepsy refractory to treatment. Initially, until the gene was discovered, it was considered an atypical form of Rett syndrome. This study aimed to describe the clinical and molecular heterogeneity in CDLK5 disorders among three female patients with CDKL5 pathogenic variants. Case reports: We reported three unrelated Mexican female patients evaluated for global developmental delay and epilepsy. All three cases were hemizygotes to a CDKL5 pathogenic variant. In one patient, we performed a 306 gene panel associated with epilepsy. In the other two cases, a human genomic microarray was performed. We describe their clinical features electroencephalogram and brain magnetic resonance evaluations. Conclusions: CDKL5 deficiency syndrome represents a challenge for clinicians since the clinical manifestations, electroencephalographic and neuroimaging studies can be non-specific. This syndrome should be suspected in the presence of global developmental delay, autistic behavioral phenotype and epilepsy, associated or not with dysmorphia. Given the similarity between various epileptic encephalopathies, multigene panels including sequencing and duplication/deletion analysis should be requested in which this gene and its possible differential diagnoses are considered, without forgetting the usefulness of genomic techniques in unclear cases.

Case report of epileptic encephalopathy caused by a new mutation of cyclin-dependent kinase-like 5 gene / 中华实用儿科临床杂志

Objective:To investigate the clinical characteristics, diagnosis and treatment status, and existing problems of early infantile epileptic encephalopathy type 2 (EIEE2) caused by de novoa mutation of cyclin-dependent kinase-like 5 gene (CDKL5).Methods:The medical history, auxiliary examination and diagnosis and treatment characteristics of 1 case with EIEE2 caused by de novoa mutation of CDKL5 gene in neonatal department of Children′s Hospital of Nanjing Medical University on August 12, 2019 were retrospectively analyzed.Combined with relevant literatures, the clinical diagnosis and treatment ideas and future prospects of this disease were summarized.Results:The patient was a female child with the age of 13 days and 23 hours.The main clinical manifestation was recurrent convulsion which was not alleviated significantly after using antiepileptic drug.The second-generation sequencing detected c. 119C>T/ p. A40V heterozygous mutation of CDKL5 gene, which was de novo mutation.Conclusions:EIEE2 caused by de novoa mutation of CDKL5 gene is a rare disease worthy of attention.Early detection and genetic diagnosis are the key to improve the diagnosis and treatment rate.

Characterization of the Relationship of CDKL5 with MeCP2 and Dnmt1 in PrimaryRat Cortical Neurons

ABSTRACT Cyclin-dependent kinase-like 5 (CDKL5) is a protein kinase that is homologous to mitogen-activated protein kinases (MAPKs) and cyclin-dependent kinases (CDKs). Mutations in the CDKL5 gene cause X-linked infantile spasms and phenotypes that overlap with that of Rett syndrome, which is a neurodevelopmental disorder caused primarily by mutations in the methyl CpG binding protein 2 gene (MECP2). Previous studies in transfected cell lines showed that CDKL5 interacts with MeCP2 and DNA (cytosine-5)-methyltransferase 1 (Dnmt1). However, little is known about the relationships of CDKL5 with interacting proteins in primary neuronal cultures. In this study, we investigated the expression patterns of CDKL5, MeCP2 and Dnmt1, and their interaction in cultured rat cortical neurons. Using real-time PCR analysis, we found that CDKL5, MeCP2 and Dnmt1 have similar expression patterns at the mRNA level. In contrast, the expression patterns of those proteins at the protein level are different and could be inversely correlated, as shown by western blotting. Using co-immunoprecipitation, we further demonstrated that CDKL5 interacts with MeCP2 and Dnmt1 in primary rat cortical neurons. These data suggest that a functional link exists among CDKL5, MeCP2 and Dnmt1 during neuronal development and may provide further insight into the pathogenesis of Rett syndrome.

Bases moleculares del síndrome de Rett, una mirada actual / Molecular basis of Rett syndrome: A current look

El síndrome de Rett (SR) es un trastorno del neurodesarrollo que afecta casi exclusivamente a niñas y cursa secundariamente con autismo. Es poco frecuente y consta de 5 formas clínicas, una clásica y el resto atípicas que comprometen de manera general la habilidad manual, el lenguaje y la motricidad amplia unida a la aparición de estereotipias y epilepsia precoz. Con el objetivo de actualizar la información sobre SR, se aplicaron los descriptores de búsqueda Síndrome de Rett, genes y «Síndrome de Rett¼, «Rett Syndrome gene¼, «Rett Syndrome¼, «Rett Syndrome gene therapy¼ y «Rett Syndrome review¼. Se investigó en los archivos digitales PubMed, Hinari, SCIELO y Medline, y se consultaron los sitios web OMIM, ORPHANET, GeneMap, Genetests, Proteins y Gene, entre otros. Entre 1.348 artículos se seleccionaron 42, los cuales reportan 3 genes causantes del síndrome: MECP2, CDKL5 y FOXG. El gen MECP2 está mutado en el 80% de los pacientes con SR clásico así como en el 40% de los afectados con alguna de sus formas atípicas. El SR con epilepsia precoz y la variante congénita se deben fundamentalmente a variaciones en los genes CDKL5 y FOXG1 respectivamente. Conclusiones: El diagnóstico del SR se basa en criterios clínicos, sin embargo, los avances en la biología molecular y en la genética en particular han abierto el abanico de posibilidades diagnósticas a las diferentes formas clínicas que antes quedaban sin clasificar, a la vez que el análisis molecular permite confirmar el criterio clínico y aportar información en cuanto al pronóstico del paciente.

Rett syndrome (RS) is a neurodevelopmental disorder that exclusively affects girls, and occurs along with autism. It is very uncommon, and has five distinct forms, one classic and the others atypical, which generally compromise manual skills, language, and mobility, and widely associated with the appearance of stereotypy and early epilepsy. With the aim of updating the information about RS, a search was performed in the computer data bases of PubMed, Hinari, SCIELO and Medline, as well as consulting other web sites including OMIM, ORPHANET, GeneMap, Genetests, Proteins and Gene, using the descriptors "Síndrome de Rett", "genes y Síndrome de Rett", "Rett Syndrome gene", "Rett Syndrome", "Rett Syndrome gene therapy", and "Rett Syndrome review". Of the 1,348 articles found, 42 articles were selected, which reported 3 genes causing the syndrome: MECP2, CDKL5 and FOXG. The MECP2 gene is mutated in 80% of patients with classic RS, as well as in 40% of those affected by any of its atypical forms. RS with early epilepsy and the congenital variant are mainly due to variations in the CDKL5 and FOXG1 genes, respectively. Conclusions: The diagnosis of RS is based on clinical criteria. However, the advances in molecular biology and genetics have opened a wide range of possibilities for diagnosing the different clinical forms that could not be classified before. Molecular analysis can help confirm the clinical criteria and provided information as regards the prognosis of the patient.