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.

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.