Cornelia de Lange Syndrome Caused by an Intragenic Heterozygous Deletion in RAD21 Detected through Very-High-Resolution Chromosomal Microarray Analysis.

Cornelia de Lange syndrome is a genetic and clinically heterogeneous entity, caused by at least five genes. It is characterized by short stature, gestalt facies, microcephaly, neurodevelopmental disorders, and other anomalies. In this report, we present a 13-year-old female patient with microcephaly, cleft palate, polydactyly, short stature, triangular facies, frontal bossing, a bulbous nose, an overfolded helix, limited pronosupination, and an anomalous uterus. No neurodevelopmental disorders were reported. A chromosomal microarray analysis of 6.5 million markers was performed in the proband and her parents. The results showed a de novo heterozygous microdeletion of exons 9-14 within RAD21, which confirmed the diagnosis of Cornelia de Lange syndrome type 4. Our patient did not show any neurologic phenotype (until the time of diagnosis), although neurodevelopmental disorders are frequently present in patients with Cornelia de Lange syndrome type 4, and despite carrying a deletion that was larger than previously reported. Therefore, unknown genetic modifiers or intrinsic mechanisms of RAD21 variants may exist and should be studied.

Utilidad diagnóstica de la secuenciación de segunda y tercera generación en pacientes con discapacidad intelectual: revisión rápida / Utility of second-generation sequencing and third-generation sequencing in the diagnosis of patients with intellectual disability: Rapid review

Introducción: la discapacidad intelectual se presenta hasta en el 18% de algunas poblaciones. Las causas son variantes genéticas puntuales y variantes en el número de copias detectadas por la secuenciación de segunda generación y el análisis cromosómico por micromatrices, respectivamente. Sin embargo, se tiene otras variantes, como las estructurales, repetición de trinucleótidos o trastornos de la impronta que solo son detectadas por otras pruebas específicas. La secuenciación de tercera generación tiene el potencial de detectar todas las variantes genéticas. El objetivo es determinar las ventajas de la secuenciación de tercera generación sobre la de segunda generación en pacientes con discapacidad intelectual. Material y métodos: búsqueda sistemática mediante los tesauros MESH «discapacidad intelectual» y «secuenciación de segunda generación»; así como el término de «secuenciación de tercera generación». Resultados: se seleccionaron 31 artículos; 9 utilizaron la secuenciación de tercera generación en pacientes con estudios genómicos previos y se encontró que el 40% tenían variantes estructurales. Los que emplearon la secuenciación de segunda generación (n = 22) determinaron mediante un metaanálisis, que detectaron variantes de un solo nucleótido y variantes en el número de copias en un 29,8 y 9,2% de los casos, respectivamente. Conclusiones: la secuenciación de tercera generación tiene la capacidad de encontrar variantes estructurales, disomías uniparentales, repetición de trinucleótidos y variantes de un solo nucleótido, lo cual permitiría tener una mayor probabilidad de establecer la etiología de la discapacidad intelectual. Sin embargo, se necesitan estudios con muestras más representativas no solo en quienes padecen de discapacidad intelectual, sino a nivel poblacional.(AU)

Introduction: Some populations have an intellectual disability frequency of nearly 18%. Among, the diverse genetic causes are single nucleotide variants and copy number variations, detected with second-generation sequencing and chromosomal microarray analysis, respectively. Nevertheless, other variants such as structural variants, trinucleotide repeat or imprinting disorders, cannot be detected by these tests and require different specific techniques. Third-generation sequencing have a power of found all variants. The purpose is to stablish the benefits of using third generation sequencing above second-generation sequencing in the diagnosis of patient with intellectual disability. Material and methods: A rapid systematic review was performed on the Medline using thesaurus terms MESH of “intellectual disability” and “second-generation sequencing”; as well as using the term “third-generation sequencing”. Results: 31 articles were selected in total. Of those, nine used third-generation sequencing in patients with previously genomic test, and founded structural variants in 40% of cases, all these variants were corroborated with other gold standard tests. Twenty-two studies used second-generation sequencing (n = 22) and showed through metanalysis, that 29,8% and 9,2% of these cases are due a single nucleotide variant and copy number variations, respectively. Conclusions: Third-generation sequencing can find structural variants, uniparental disomies, trinucleotide repeat and single nucleotide variation. Therefore, it would allow a broader and better study of the etiology of intellectual disability. Nevertheless, more research with larger representative samples in patients and healthy population is needed.(AU)

The ESX-4 substrates, EsxU and EsxT, modulate Mycobacterium abscessus fitness.

ESX type VII secretion systems are complex secretion machineries spanning across the mycobacterial membrane and play an important role in pathogenicity, nutrient uptake and conjugation. We previously reported the role of ESX-4 in modulating Mycobacterium abscessus intracellular survival. The loss of EccB4 was associated with limited secretion of two effector proteins belonging to the WXG-100 family, EsxU and EsxT, and encoded by the esx-4 locus. This prompted us to investigate the function of M. abscessus EsxU and EsxT in vitro and in vivo. Herein, we show that EsxU and EsxT are substrates of ESX-4 and form a stable 1:1 heterodimer that permeabilizes artificial membranes. While expression of esxU and esxT was up-regulated in M. abscessus-infected macrophages, their absence in an esxUT deletion mutant prevented phagosomal membrane disruption while maintaining M. abscessus in an unacidified phagosome. Unexpectedly, the esxUT deletion was associated with a hyper-virulent phenotype, characterised by increased bacterial loads and mortality in mouse and zebrafish infection models. Collectively, these results demonstrate that the presence of EsxU and EsxT dampens survival and persistence of M. abscessus during infection.

Variantes en el número de copias en trastornos del neurodesarrollo, síndrome malformativo y talla baja en Perú / Copy number variation in development disorders, malformative syndrome and short stature in Peru

RESUMEN Objetivo : determinar las variantes en el número de copias y regiones de homocigosidad mediante el análisis cromosómico por micromatrices, en niños con diagnóstico de trastorno del neurodesarrollo: retraso del desarrollo psicomotor (RDPM), discapacidad intelectual (DI) y trastorno del espectro autista (TEA), así como pacientes con síndrome malformativo (SM) y talla baja idiopática (TBI). Materiales y métodos : se evaluaron a 367 niños peruanos diagnosticados clínicamente con DI, RDPM, TEA, TBI y SM a quienes se les realizó el análisis cromosómico por micromatrices (CMA 750K CGH+SNP) en sangre periférica, entre los años 2016-2018. Resultados : las edades fluctuaron entre los 4,8 meses y los 18 años, con una media de 5,6 años. Los diagnósticos más frecuentes fueron RDPM (48%) y DI (30%). Se reportaron resultados anormales (variantes patogénicas, probablemente patogénicas, disomías uniparentales y regiones de homocigosidad superiores a 2,56%) en el 50,3% de los pacientes. Los resultados anormales se observaron en el 53,3% de los casos con diagnóstico de DI y el 47,9% de RDPM; mientras que en el resto de los casos con TBI sindrómica, SM y TEA tuvieron resultados anormales en el 52,4%, 52% y 20% respectivamente. Por otro lado, encontramos hasta un 6,2% de los padres eran consanguíneos no declarados. Conclusiones : la tasa de detección de las variantes en el número de copias (CNVs) encontrada en nuestro estudio fue superior a la reportada en estudios internacionales independientemente del diagnóstico clínico. Además, se pudo encontrar una mayor frecuencia de consanguinidad no declarada con relación a estudios anteriores.

ABSTRACT Objective: To establish the ratios of the copy number variations and regions of homozygosity through chromosomal microarray analysis (CMA) in children with neurodevelopmental disorders: development delay (DD), intellectual disability (ID), and/or autistic spectrum disorder (ASD), malformative syndrome (MS) and idiopathic short stature (ISS). Materials and Methods: We evaluated 367 Peruvian children diagnosed clinically with ID, DD, ASD, ISS and MS to whom performed chromosomal microarray analysis in peripheral blood (750K CGH + SNP), between the years 2016-2018. Results: Patients' age fluctuated between 4.8 months and 18 years old, with an average of 5.6 years old. The most frequent diagnoses were development delay (48%) and intellectual disability (30%). Abnormal results (pathogenic variants, likely pathogenic variants, uniparental disomies and loss of heterozygosity> 2.5%) were reported in 50.3%. The 53.28% of the cases with a diagnosis of intellectual disability and 47.92% of development delay showed abnormal results; while the children with short stature syndromic, malformative syndrome, and autistic disorders spectrum disorders showed abnormal results in 52.38%, 52% and 20% respectively. Additionally, we found that 6.25% of parents were non-declared consanguinity. Conclusions: Abnormal results found in our study was a higher ratio than other international reports regardless of the clinical diagnosis. Furthermore, we show a most rate of non-declared consanguinity in relation with previous reports.

GATAD2B Gene Microdeletion Causing Intellectual Disability Autosomal Dominant Type 18: Case Report and Review of the Literature.

Pathogenic variants of the GATAD2B gene (1q21.3) are linked to intellectual disability autosomal dominant type 18 (MRD18; MIM 615074), characterized by dysmorphic features, psychomotor and language delay. We present an 11-year-old female patient with intellectual disability and typical clinical characteristics of MRD18. Chromosomal microarray analysis (CMA) revealed a novel CNV, approximately 200 kb in size and showed that the INTS3 and SLC27A3 genes are completely deleted along with the first 10 exons of the GATAD2B gene. INTS3 encodes the integrator complex subunit 3 and is part of the complex that maintains genome stability; SLC27A3 encodes a fatty acid transporter and has been associated with autism spectrum disorder. GATAD2B haploinsufficiency is associated with the phenotype. Furthermore, the girl had other clinical characteristics not previously described, such as emotional instability, calf hypotrophy, hypoplastic digit pads, tapered thumbs, and anterior earlobe crease. This study highlights the importance of the phenotype-genotype correlation using molecular diagnostic techniques, such as CMA, and its impact on precise diagnosis, treatment, prognosis, and genetic counseling for patients and their families.

Homozygous Deletion of the CFTR Gene Caused by Interstitial Maternal Isodisomy in a Peruvian Child with Cystic Fibrosis.

We report the first case in Peru of cystic fibrosis caused by a homozygous deletion of the cystic fibrosis transmembrane conductance regulator ( CFTR ) gene. A 10-month-old child who presented with meconium ileus and pancreatic insufficiency was tested for cystic fibrosis. Both parents of the child are of Peruvian background, are nonconsanguineous, and have no personal or family history of the disease. Chromosome microarray analysis revealed a homozygous deletion of the CFTR gene on chromosome 7 (7q31.2) within a maternally derived 12.8-Mb region of loss of heterozygosity with deletion of a region that includes the CFTR gene. Parental testing confirmed this finding. This case highlights the great importance of molecular testing and the study of chromosomal rearrangements in reaching a correct diagnosis and providing proper genetic counseling to the affected families.

Colonización intraluminal en túbulos seminíferos en ratón / Intraluminal colonization into the seminiferous tubules in mice

Using the primordial germ cells transplant technique, we could be able preserve and multiply pluripotent cells in the receptor for a long period of time. In this work, we aim to evaluate intraluminal colonization of a cellular gonocyte suspension from 14.5 dpc fetus. Cellular suspension with PGC’s were isolated from fetus male mice by two enzymatic digestion steps, and cellular suspensions were transplanted into the rete testis of the receptor animals that were previously injected with Busulfan to decrease their own spermatogenesis. In this research the intraluminal colonization was identified in 13.27%, demonstrating that transplantation of a cellular suspension from gonocytes of fetus of 14.5 dpc containing PGCs can colonize the seminiferous tubules and support the spermatogenesis.

Con la técnica de trasplante de células germinales primordiales es posible preservar y multiplicar células pluripotentes en el receptor durante un largo periodo de tiempo. Nuestro objetivo fue evaluar la colonización intraluminal de una suspensión celular de gonocitos de 14,5 dpc obtenidos de fetos. La suspensión celular de CGP fueron aislados de fetos de ratones machos mediante dos pasos de digestión enzimática; luego, las suspensiones celulares fueron trasplantadas en la rete testis de los animales receptores los cuales fueron tratados previamente con Busulfan para disminuir su propia espermatogénesis. En esta investigación se comprobó la colonización intraluminal en 13,27%, lo que demuestra que el trasplante de una suspensión celular de gonocitos del feto de 14,5 dpc que contiene CGP pueden colonizar los túbulos seminíferos y además promover su propia espermatogénesis.