Homozygous TNNI3 frameshift variant in a consanguineous family with lethal infantile dilated cardiomyopathy.

BACKGROUND: Dilated cardiomyopathy (DCM) is characterized by dilatation of the left ventricle, systolic dysfunction, and normal or reduced thickness of the left ventricular wall. It is a leading cause of heart failure and cardiac death at a young age. Cases with neonatal onset DCM were correlated with severe clinical presentation and poor prognosis. A monogenic molecular etiology accounts for nearly half of cases. FAMILY DESCRIPTION: Here, we report a family with three deceased offspring at the age of 1 year old. The autopsy of the first deceased infant revealed a DCM. The second infant presented a DCM phenotype with a severely reduced Left Ventricular Ejection Fraction (LVEF) of 10%. Similarly, the third infant showed a severe DCM phenotype with LVEF of 30% as well, in addition to eccentric mitral insufficiency. RESULTS: Exome sequencing was performed for the trio (the second deceased infant and her parents). Data analysis following the autosomal dominant and recessive patterns of inheritance was carried out along with a mitochondrial pathways-based analysis. We identified a homozygous frameshift variant in the TNNI3 gene (c.204delG; p.(Arg69AlafsTer8)). This variant has been recently reported in the ClinVar database in association with cardiac phenotypes as pathogenic or likely pathogenic and classified as pathogenic according to ACMG. CONCLUSION: Genetic counseling was provided for the family and a prenatal diagnosis of choronic villus was proposed in the absence of pre-implantation genetic diagnosis possibilities. Our study expands the case series of early-onset DCM patients with a protein-truncating variant in the TNNI3 gene by reporting three affected infant siblings.

Catalyzing precision: unraveling the diagnostic conundrum of tunisian familial hypophosphatasia case through integrative clinical and molecular approaches.

Familial Hypophosphatasia presents a complex diagnostic challenge due to its wide-ranging clinical manifestations and genetic heterogeneity. This study aims to elucidate the molecular underpinnings of familial Hypophosphatasia within a Tunisian family harboring a rare c.896 T > C mutation in the ALPL gene, offering insights into genotype-phenotype correlations and potential therapeutic avenues. The study employs a comprehensive approach, integrating biochemical examination, genetic analysis, structural modeling, and functional insights to unravel the impact of this rare mutation. Genetic investigation revealed the presence of the p.Leu299Pro mutation within the ALPL gene in affected family members. This mutation is strategically positioned in proximity to both the catalytic site and the metal-binding domain, suggesting potential functional consequences. Homology modeling techniques were employed to predict the 3D structure of TNSALP, providing insights into the structural context of the mutation. Our findings suggest that the mutation may induce conformational changes in the vicinity of the catalytic site and metal-binding domain, potentially affecting substrate recognition and catalytic efficiency. Molecular dynamics simulations were instrumental in elucidating the dynamic behavior of the tissue-nonspecific alkaline phosphatase isozyme (TNSALP) in the presence of the p.Leu299Pro mutation. The simulations indicated alterations in structural flexibility near the mutation site, with potential ramifications for the enzyme's overall stability and function. These dynamic changes may influence the catalytic efficiency of TNSALP, shedding light on the molecular underpinnings of the observed clinical manifestations within the Tunisian family. The clinical presentation of affected individuals highlighted significant phenotypic heterogeneity, underscoring the complex genotype-phenotype correlations in familial Hypophosphatasia. Variability in age of onset, severity of symptoms, and radiographic features was observed, emphasizing the need for a nuanced understanding of the clinical spectrum associated with the p.Leu299Pro mutation. This study advances our understanding of familial Hypophosphatasia by delineating the molecular consequences of the p.Leu299Pro mutation in the ALPL gene. By integrating genetic, structural, and clinical analyses, we provide insights into disease pathogenesis and lay the groundwork for personalized therapeutic strategies tailored to specific genetic profiles. Our findings underscore the importance of comprehensive genetic and clinical evaluation in guiding precision medicine approaches for familial Hypophosphatasia.

[Chemotherapy-induced febrile neutropenia in a Tunisian Department of Pediatric Oncology]. / Neutropénie fébrile chimio-induite dans une unité d'oncologie pédiatrique tunisienne.

Chemotherapy-induced neutropenia (FN) is the most common infectious complication in pediatric oncology. To our knowledge, no pediatric research has been published in Tunisia. The purpose of our study was to describe the features of FN among Tunisian children and to investigate factors correlated with FN. We conducted a prospective study of children with chemotherapy-induced FN at the Department of Pediatric Medicine A of the Tunis Children´s Hospital from July 2019 to December 2019. We recorded 50 episodes of FN in 32 patients whose mean age was 5.3 years (3 months-16 years). We included 26 patients with solid tumors (81%) and six patients with hemopathies (18.7%). The mean time between last treatment and fever onset was 10.67 days. Bacteriological investigation was contributory in 18% of cases and mainly showed gram positive cocci. Therapeutic protocol including 1st line empirical antibiotic therapy (3rd generation cephalosporin with aminoglycoside) was effective in 62% of cases. Mortality rate of patients with FN was 2%. The statistical study did not reveal any factor of correlation with late-onset neutropenia. In conclusion, our results are consistent with literature data on bacteriological documentation and mortality. Our 1st line treatment option based on 3rd generation cephalosporin associated with aminoglycoside was effective in 2/3 of the cases. In the future, oral antibiotics may be considered in patients at low risk for infection.

Scurvy still exists in children: A case report.

Scurvy is one of the oldest diseases known to mankind. Although rare lately, the clinical suspicion arises in front of a precarious situation or deficient nutrition and food restriction secondary to a psychiatric condition, even in patients with non-specific complaints. We report the observation of a 6 -year- old boy, followed for autism since the age of 3 years and who was admitted for limping, hemorrhagic syndrome, arthritis and weakness. The diagnosis of child abuse was initially suspected but clinical and radiological abnormalities seen were characteristic of scurvy. Vitamin C level was undetectable. The child had an unbalanced diet.A favorable outcome was rapidly obtained following supplementation. Scurvy is rare, but it should be mentioned among children with psychiatric disorders, presenting with musculoskeletal manifestations or hemorrhagic syndrome. It is essential to prevent it by systematic dietary supplementation of vitamin C in children with eating difficulties.

The LIM domain binding protein 1, Ldb1, has distinct roles in Neu-induced mammary tumorigenesis.

We have previously shown that the Ste20-like kinase SLK interacts directly with the LIM domain-binding protein 1, Ldb1. Ldb1 knock down in murine fibroblasts activates SLK and enhances cell migration. To investigate the effect of Ldb1 deletion in ErbB2/HER2-driven tumorigenesis, Ldb1 conditional mice were crossed into MMTV-NIC mice, expressing the Neu oncogene and Cre recombinase from a bi-cistronic transgene. Our results show that Ldb1 is expressed in the mammary epithelium and that deletion of Ldb1 does not impair mammary gland development. Although high levels of Ldb1 can be correlated with poor prognosis in HER2+ breast cancers, Ldb1 ablation does not affect Neu-induced tumor progression in transgenic mice. Surprisingly, Ldb1 deletion did not affect SLK kinase activity in primary tumors or established cell lines. Nevertheless, Ldb1-deficient tumor cells showed enhanced mesenchymal and migratory characteristics in vitro. However, Ldb1-null cells failed to colonize the lungs of wildtype female mice when injected into the tail vein. Together our results show that Ldb1 is dispensable for mammary gland development and Neu-induced tumor progression but required for dissemination at secondary sites. Furthermore, our data also highlight contrasting cell line behaviours observed from in vivo and in vitro assays.