Asociación entre la mutación homocigota c.318A>T en el exón 2 del gen EIF2B5 y la forma infantil de la leucoencefalopatía con sustancia blanca evanescente / Association between homozygous c.318A>GT mutation in exon 2 of the EIF2B5 gene and the infantile form of vanishing white matter leukoencephalopathy

Resumen: Introducción: La leucoencefalopatía con sustancia blanca evanescente es una de las leucodistrofias más frecuentes. Generalmente inicia en la infancia y presenta un patrón de herencia autosómica recesiva. El 90% de los casos manifiesta mutaciones en uno de los genes que codifican para las cinco subunidades del factor de iniciación eucariótica 2 (EIF2B5). El diagnóstico se realiza por las manifestaciones clínicas, hallazgos en la resonancia magnética cerebral y estudios moleculares confirmatorios. Caso clínico: Paciente masculino de 13 meses con neurodesarrollo previo normal. Antecedente de internamiento por vómito, hipertermia, irritabilidad y rechazo a la vía oral de 15 días de evolución. Ante la exploración presentó perímetro cefálico y pares craneales normales. Se encontró hipotónico, con reflejos incrementados, sin datos meníngeos ni de cráneo hipertensivo. La tomografía de cráneo mostró hipodensidad generalizada de la sustancia blanca. Egresó sin recuperar deambulación. A los 15 días presentó somnolencia y crisis convulsivas focales después de traumatismo craneoencefálico. En la resonancia magnética se observó hipointensidad generalizada de sustancia blanca. Ante la sospecha de leucoencefalopatía con sustancia blanca evanescente, se solicitó la secuenciación del gen EIF2B5, que reportó mutación homocigota c.318A>T en el exón 2. El paciente requirió múltiples hospitalizaciones por hipertermia y descontrol de crisis convulsivas. Posteriormente mostró deterioro cognitivo, motor y pérdida de la agudeza visual. Falleció a los 6 años por neumonía severa. Conclusiones: Este caso contribuye a conocer el espectro de mutaciones que se presenta en pacientes mexicanos y permite ampliar el fenotipo asociado con esta mutación.

Abstract: Background: Vanishing white matter disease is one of the most frequent leukodystrophies in childhood with an autosomal recessive inheritance. A mutation in one of the genes encoding the five subunits of the eukaryotic initiation factor 2 (EIF2B5) is present in 90% of the cases. The diagnosis can be accomplished by the clinical and neuroradiological findings and molecular tests. Case report: We describe a thirteen-month-old male with previous normal neurodevelopment, who was hospitalized for vomiting, hyperthermia and irritability. On examination, cephalic perimeter and cranial pairs were normal. Hypotonia, increased muscle stretching reflexes, generalized white matter hypodensity on cranial tomography were found. Fifteen days after discharge, he suffered minor head trauma presenting drowsiness and focal seizures. Magnetic resonance showed generalized hypointensity of white matter. Vanishing white matter disease was suspected, and confirmed by sequencing of the EIF2B5 gene, revealing a homozygous c.318A> T mutation in exon 2. Subsequently, visual acuity was lost and cognitive and motor deterioration was evident. The patient died at six years of age due to severe pneumonia. Conclusions: This case contributes to the knowledge of the mutational spectrum present in Mexican patients and allows to extend the phenotype associated to this mutation.

Novel mutations identified in EIF2B5 gene in Kashmiri patients as susceptibility factor for multiple sclerosis.

White matter disease refers to a set of diseases that affect the white matter of the brain and all of which have different consequences on brain function. Most of the studies have shown that it results from the defects during protein synthesis, with the gene defects in EIF2B1–5, encoding the five subunits of eukaryotic translation initiation factor 2B (eIF2B) α, β, γ, δ and ε, respectively. eIF2B plays a crucial role in protein translation and its regulation under different conditions. The previous studies have shown that mutations in five subunits of eIF2B cause white matter disease of the brain and thus EIF2B is the main culprit in development of white matter disease. In this study, the mutational screening of EIF2B5 gene encoding eIF2Bε was performed for the first time in 12 Kashmiri patients, each having a unique white matter disease condition. We found two novel missense mutations in EIF2B5: c.580A>G, p.Thr194Ala and c.611C>T, p.Ala204Val among the patients with demyelinating disease (multiple sclerosis), but no mutation was found in other patients. In conclusion our study suggests involvement of the EIF2B5 gene in MS development, thus suggesting p.Thr194Ala to be a susceptibility factor for the development of multiple sclerosis.