Moyamoya Angiopathy: An Underdiagnosed Cause of Ischemic Stroke in a Tunisian Pediatric Cohort.

BACKGROUND: Moyamoya angiopathy is a rare cerebral vasculopathy and an underdiagnosed cause of arterial ischemic stroke in children. We aim to report the clinical and radiological presentations in a Tunisian pediatric cohort. METHODS: We identified moyamoya angiopathy in pediatric patients managed at the Child Neurology Department of Hedi Chaker Sfax University Hospital between 2008 and 2020 and reviewed their clinical and radiological data as well as their evolutionary profile. RESULTS: We collected 14 patients with median age 40.6 months and a female predominance (sex ratio of 0.75). An arterial ischemic stroke (AIS) revealed the disease in all patients, with the major symptom being a motor deficit. Symptoms related to a transient ischemic attack before the diagnostic consultation were reported in four patients. Carotid territory was, clinically and radiologically, the most frequently involved. Brain magnetic resonance imaging with angiography was performed in 12 patients confirming the diagnosis by revealing the development of collateral vessels. All the investigations concluded to moyamoya disease in 57.2% and moyamoya syndrome in 42.8%. The latter was related to Down syndrome in five patients and neurofibromatosis type 1 in one patient. With a mean follow-up of 2.35 years, two patients had at least two more AISs during the first two years following diagnosis and 42.8% of patients were diagnosed with vascular or poststroke epilepsy. Full recovery was noted in 14.3% of cases. CONCLUSIONS: Moyamoya angiopathy in children is a serious condition that needs to be recognized due to the high risk of recurrent ischemic strokes.

Case report: Compound heterozygous variants detected by next-generation sequencing in a Tunisian child with ataxia-telangiectasia.

Ataxia-telangiectasia (A-T) is an autosomal recessive primary immunodeficiency disorder (PID) caused by biallelic mutations occurring in the serine/threonine protein kinase (ATM) gene. The major role of nuclear ATM is the coordination of cell signaling pathways in response to DNA double-strand breaks, oxidative stress, and cell cycle checkpoints. Defects in ATM functions lead to A-T syndrome with phenotypic heterogeneity. Our study reports the case of a Tunisian girl with A-T syndrome carrying a compound heterozygous mutation c.[3894dupT]; p.(Ala1299Cysfs3;rs587781823), with a splice acceptor variant: c.[5763-2A>C;rs876659489] in the ATM gene that was identified by next-generation sequencing (NGS). Further genetic analysis of the family showed that the mother carried the c.[5763-2A>C] splice acceptor variant, while the father harbored the c.[3894dupT] variant in the heterozygous state. Molecular analysis provides the opportunity for accurate diagnosis and timely management in A-T patients with chronic progressive disease, especially infections and the risk of malignancies. This study characterizes for the first time the identification of compound heterozygous ATM pathogenic variants by NGS in a Tunisian A-T patient. Our study outlines the importance of molecular genetic testing for A-T patients, which is required for earlier detection and reducing the burden of disease in the future, using the patients' families.

Juvenile Dermatomyositis Without Skin Lesions in an Antinuclear Matrix Protein 2 Antibody Seropositive Pediatric Case.

ABSTRACT: We report a 5-year-old boy who presented with progressive weakness in 4 limbs and gait disorders over 7 months. No skin rash was observed on admission. A symmetrical proximodistal weakness was found. The creatine kinase level was normal with a slightly elevated lactate dehydrogenase level. Biopsy specimens showed infiltration of mononuclear cells, few necrotic fibers, and perifascicular atrophy. Screening for myositis-specific antibodies was positive for the antinuclear matrix protein 2 antibody, which is mainly associated with dermatomyositis. Symptoms improved on receiving corticosteroids. Our findings suggest that in cases where inflammatory muscle disease is suspected, antinuclear matrix protein 2 antibody analyses should be considered for precise diagnosis, even with the absence of dermatological symptoms. The case suggests consideration of juvenile dermatomyositis in children with no associated skin manifestations or elevated creatine kinase levels and highlights the importance of screening for myositis-specific antibodies in helping with the diagnosis, given the possible heterogeneity of its clinical presentations.

Customized targeted massively parallel sequencing enables the identification of novel pathogenic variants in Tunisian patients with Developmental and Epileptic Encephalopathy.

OBJECTIVE: To develop a high throughput sequencing panel for the diagnosis of developmental and epileptic encephalopathy in Tunisia and to clarify the frequency of disease-causing genes in this region. METHODS: We developed a custom panel for next generation sequencing of the coding sequences of 116 genes in individuals with developmental and epileptic encephalopathy from the Tunisian population. Segregation analyses as well as in silico studies have been conducted to assess the identified variants' pathogenicity. RESULTS: We report 12 pathogenic variants in SCN1A, CHD2, CDKL5, SZT2, KCNT1, GNAO1, PCDH19, MECP2, GRIN2A, and SYNGAP1 in patients with developmental and epileptic encephalopathy. Five of these variants are novel: "c.149delA, p.(Asn50MetfsTer26)" in CDKL5; "c.3616C>T, p.(Arg1206Ter)" in SZT2; "c.111_113del, p.(Leu39del)" in GNAO1; "c.1435G>C , p.(Asp479His)" in PCDH19; as well as "c.2143delC, p. (Arg716GlyfsTer10)"in SYNGAP1. Additionally, for four of our patients, the genetic result facilitated the choice of the appropriate treatment. SIGNIFICANCE: This is the first report of a custom gene panel to identify genetic variants implicated in developmental and epileptic encephalopathy in the Tunisian population as well as the North African region (Tunisia, Egypt, Libya, Algeria, Morocco) with a diagnostic rate of 30%. This high-throughput sequencing panel has considerably improved the rate of positive diagnosis of developmental and epileptic encephalopathy in the Tunisian population, which was less than 15% using Sanger sequencing. The benefit of genetic testing in these patients was approved by both physicians and parents.

A Novel Mutation in the MAP7D3 Gene in Two Siblings with Severe Intellectual Disability and Autistic Traits: Concurrent Assessment of BDNF Functional Polymorphism, X-Inactivation and Oxidative Stress to Explain Disease Severity.

Intellectual disabilities (ID) and autism spectrum disorders (ASD) are characterized by extreme genetic and phenotypic heterogeneity. However, understanding this heterogeneity is difficult due to the intricate interplay among multiple interconnected genes, epigenetic factors, oxidative stress, and environmental factors. Employing next-generation sequencing (NGS), we revealed the genetic cause of ID and autistic traits in two patients from a consanguineous family followed by segregation analysis. Furthermore, in silico prediction methods and 3D modeling were conducted to predict the effect of the variants. To establish genotype-phenotype correlation, X-chromosome inactivation using Methylation-specific PCR and oxidative stress markers were also investigated. By analyzing the NGS data of the two patients, we identified a novel frameshift mutation c.2174_2177del (p.Thr725MetfsTer2) in the MAP7D3 gene inherited from their mother along with the functional BDNF Val66Met polymorphism inherited from their father. The 3D modeling demonstrated that the p.Thr725MetfsTer2 variant led to the loss of the C-terminal tail of the MAP7D3 protein. This change could destabilize its structure and impact kinesin-1's binding to microtubules via an allosteric effect. Moreover, the analysis of oxidative stress biomarkers revealed an elevated oxidative stress in the two patients compared to the controls. To the best of our knowledge, this is the first report describing severe ID and autistic traits in familial cases with novel frameshift mutation c.2174_2177del in the MAP7D3 gene co-occurring with the functional polymorphism Val66M in the BDNF gene. Besides, our study underlines the importance of investigating combined genetic variations, X-chromosome inactivation (XCI) patterns, and oxidative stress markers for a better understanding of ID and autism etiology.

A new case with the recurrent PURA p.(Phe233del) pathogenic variant: Expansion of the phenotype and review of the literature.

In the process of neuronal development, the protein Purα (encoded by the PURA gene) is essential for neuronal proliferation, dendritic maturation, and the transportation of mRNA to translation sites. Mutations in the PURA gene may alter normal brain development and impair neuronal function, contributing to developmental delays and seizures. Recently, PURA syndrome is described as developmental encephalopathy with or without epilepsy, neonatal hypotonia, feeding difficulties, global developmental delay, and severe intellectual disability. In our study, we aimed to perform a genetic analysis by whole exome sequencing (WES) in a Tunisian patient presented with developmental and epileptic encephalopathy to provide a molecular explanation for the developed phenotype. We collected, also, clinical data of all PURA p.(Phe233del) patients reported yet and compared the clinical features with those of our patient. Results revealed the presence of the known PURA c.697_699del, p.(Phe233del) variant. Our studied case shares some clinical features including hypotonia, feeding difficulties, severe developmental delay, epilepsy, and language delay (nonverbal) but presents a radiological finding undescribed before. Our finding defines and expands the phenotypic and genotypic spectrum of the PURA syndrome supporting the absence of reliable genotype-phenotype correlations and the existence of a highly variable, wide-ranging clinical spectrum.

Case report: Functional analysis of the p.Arg507Trp variant of the PIGT gene supporting the moderate epilepsy phenotype of mutations in the C-terminal region.

Pathogenic germline variants in the PIGT gene are associated with the "multiple congenital anomalies-hypotonia-seizures syndrome 3" (MCAHS3) phenotype. So far, fifty patients have been reported, most of whom suffer from intractable epilepsy. Recently, a comprehensive analysis of a cohort of 26 patients with PIGT variants has broadened the phenotypical spectrum and indicated that both p.Asn527Ser and p.Val528Met are associated with a milder epilepsy phenotype and less severe outcomes. Since all reported patients are of Caucasian/Polish origin and most harbor the same variant (p.Val528Met), the ability to draw definitive conclusions regarding the genotype-phenotype correlation remains limited. We report a new case with a homozygous variant p.Arg507Trp in the PIGT gene, detected on clinical exome sequencing. The North African patient in question displays a predominantly neurological phenotype with global developmental delay, hypotonia, brain abnormalities, and well-controlled epileptic seizures. Homozygous and heterozygous variants in codon 507 have been reported to cause PIGT deficiency without biochemical confirmation. In this study, FACS analysis of knockout HEK293 cells that had been transfected with wild-type or mutant cDNA constructs demonstrated that the p.Arg507Trp variant leads to mildly reduced activity. Our result confirm the pathogenicity of this variant and strengthen recently reported evidence on the genotype-phenotype correlation of the PIGT variant.

Combined in Silico Prediction Methods, Molecular Dynamic Simulation, and Molecular Docking of FOXG1 Missense Mutations: Effect on FoxG1 Structure and Its Interactions with DNA and Bmi-1 Protein.

FoxG1 encoded by FOXG1 gene is a transcriptional factor interacting with the DNA of targeted genes as well as with several proteins to regulate the forebrain development. Mutations in the FOXG1 gene have been shown to cause a wide spectrum of brain disorders, including the congenital variant of Rett syndrome. In this study, the direct sequencing of FOXG1 gene revealed a novel c.645C > A (F215L) variant in the patient P1 and a de novo known one c.755G > A (G252D) in the patient P2. To investigate the putative impact of FOXG1 missense variants, a computational pipeline by the application of in silico prediction methods, molecular dynamic simulation, and molecular docking approaches was used. Bioinformatics analysis and molecular dynamics simulation have demonstrated that F215L and G252D variants found in the DNA binding domain are highly deleterious mutations that may cause the protein structure destabilization. On the other hand, molecular docking revealed that F215L mutant is likely to have a great impact on destabilizing the protein structure and the disruption of the Bmi-1 binding site quite significantly. Regarding G252D mutation, it seems to abolish the ability of FoxG1 to bind DNA target, affecting the transcriptional regulation of targeted genes. Our study highlights the usefulness of combined computational approaches, molecular dynamic simulation, and molecular docking for a better understanding of the dysfunctional effects of FOXG1 missense mutations and their role in the etiopathogenesis as well as in the genotype-phenotype correlation.

8q21.11 microdeletion syndrome: Delineation of HEY1 as a candidate gene in neurodevelopmental and cardiac defects.

BACKGROUND: 8q21.11 microdeletion syndrome is a rare chromosomal disorder characterized by recurrent dysmorphic features, a variable degree of intellectual disability and ocular, cardiac and hand/feet abnormalities. To date, ZFHX4 is the only candidate gene implicated in the ocular findings. In this study, we evaluated a patient with a de novo 8q21.13-21.3 deletion to define a new small region of overlap (SRO) for this entity. METHODS: We conducted a clinical evaluation and comparative genomic hybridization (CGH) 4x44K microarrays in a patient with de novo unbalanced translocation t(8;16)(q21; q11.2). RESULTS: The case, a 6-year-old boy, presented dysmorphic features including an elongated face, brachycephaly with a high forehead, an underdeveloped ala, thin upper lip, micrognathia, low-set ears, hypotonia, mild intellectual disability, cortical atrophy with thin corpus callosum defect, and an atrial septal defect. No ocular abnormalities were found. Microarray analysis revealed a 9.6 Mb interstitial 8q21.11-21.3 deletion, not including the ZFHX4 gene. This microdeletion was confirmed in our patient through qPCR analysis, and both parents had a normal profile. Alignment analysis of our case defined a new SRO encompassing five genes. Among them, the HEY1 gene is involved in the embryonic development of the heart, central nervous system, and vascular system. Hrt1/Hey1 null mice show perinatal lethality due to congenital malformations of the aortic arch and its branch arteries. HEY1 has also been linked to the maintenance of neural stem cells, inhibition of oligodendrocyte differentiation, and myelin gene expression. CONCLUSION: HEY1 is a candidate gene for both neurological and cardiac features of the 8q21.11 microdeletion syndrome and might, therefore, explain specific components of its pathophysiology.