Leucoencefalopatía megalencefálica con quistes: importancia de la descripción clínica en la era genética / Megalencephalic leukoencephalopathy with cysts -the clinical importance in the genetic era

INTRODUCCIÓN: La leucoencefalopatía megalencefálica con quistes es una leucodistrofia de origen genético que produce una alteración de la homeostasis del agua e iones en el cerebro, generando formas vacuolares y edema crónico en la sustancia blanca con deterioro neurológico progresivo. Debe sospecharse en los lactantes que presentan macrocefalia progresiva durante el primer año de vida, retraso motor y hallazgos característicos en la resonancia magnética cerebral. CASO CLÍNICO: Niña en seguimiento desde los 9 meses por macrocefalia progresiva y retraso del desarrollo psicomotor con presencia en la resonancia magnética cerebral de hallazgos compatibles con leucoencefalopatía megalencefálica con quistes, y aparición de epilepsia en su evolución. Los estudios genéticos habituales (secuenciación de nueva generación y array) fueron negativos, pero, al cumplir los criterios diagnósticos, se procedió al estudio del ARN mensajero y el ADN complementario, que confirmó la presencia de dos variantes patogénicas en MLC1. CONCLUSIONES: La leucoencefalopatía megalencefálica con quistes es una entidad infrecuente. Es característica la macrocefalia progresiva en el primer año de vida, la ausencia de deterioro o deterioro lento, y la posibilidad de desarrollar epilepsia, espasticidad y ataxia en su evolución. Cobra importancia en dichos pacientes la realización de una prueba de imagen que muestre hallazgos propios de la entidad, lo que, junto con la clínica, permite diferenciarla de otras leucodistrofias y establecer un diagnóstico confirmatorio. Los estudios genéticos pueden constatar la mutación asociada que posibilita predecir el fenotipo clinicorradiológico

INTRODUCTION: Megalencephalic leukoencephalopathy with cysts is a leukodystrophy of genetic origin that produces an alteration in the water and ion homeostasis in the brain, generating vacuolar forms and chronic oedema in the white matter with progressive neurological deterioration. It should be suspected in infants who present progressive macrocephaly during the first year of life, motor retardation and characteristic findings in magnetic resonance brain scans. CASE REPORT: We report the case of a girl who was followed up from the age of 9 months due to progressive macrocephaly and delayed psychomotor development and brain MRI findings consistent with megalencephalic leukoencephalopathy with cysts, and the appearance of epilepsy during its development. The usual genetic studies (new generation sequencing and array) were negative, but as the diagnostic criteria were met, a complementary messenger RNA and DNA study was conducted, which confirmed the presence of two pathogenic variants in MLC1. CONCLUSIONS: Megalencephalic leukoencephalopathy with cysts is a rare condition. Progressive macrocephaly in the first year of life, the absence of deterioration or slow deterioration, and the possibility of developing epilepsy, spasticity and ataxia are characteristic signs in its course. It is important for these patients to undergo an imaging test that shows findings that characterise this condition, which, together with the clinical features, makes it possible to differentiate it from other leukodystrophies and to establish a confirmatory diagnosis. Genetic studies can confirm the associated mutation that makes it possible to predict the clinicoradiological phenotype

The effect of copy number variations in chromosome 16p on body weight in patients with intellectual disability.

Syndromic monogenic obesity is a rare and severe early-onset form of obesity. It is characterized by intellectual disability, congenital malformations, and/or dysmorphic facies. The diagnosis of patients is challenging due to the genetic heterogenicity of this condition. However, the use of microarray technology in combination with public databases has been successful on genotype-phenotype correlations, especially for body mass index (BMI) alteration. In this study, the relationship between copy number variations (CNVs) detected by microarray mapping on 16p region and BMI alterations in syndromic patients were assessed. In order to achieve this goal, 680 unrelated Spanish children with intellectual disability were included. 16p region was characterized by using microarray platforms. All detected variants were classified as: (I) one previously non-described 10-Mb duplication in 16p13.2p12.3 region considered causal of intellectual disability and severe overweight, and (II) eleven 16p11.2 CNVs of low prevalence but with recurrence in syndromic patients with severe BMI alteration (nine proximal and two distal). Proximal 16p11.2 CNVs have a dose-dependent effect: underweight in carriers of duplication and obesity in carriers of deletion. KCTD13 was identified as a possible candidate gene for BMI alteration on proximal syndromes, whereas SH2B1 gene was identified as candidate for distal syndromes. The results shown in this paper suggest that syndromic patients could constitute a reliable model to evaluate hypothalamic satiety and obesity disorders as well as generate a wide expectation for primary prevention of comorbidities. Furthermore, 16p13.2p12.3 showed to be an important region on the regulation of body fatness.