Case Report and Review of the Literature: Congenital Diaphragmatic Hernia and Craniosynostosis, a Coincidence or Common Cause?

Pivotal role of BCL11B in the immune, hematopoietic and nervous systems: a review of the BCL11B-associated phenotypes from the genetic perspective

The transcription factor BCL11B plays an essential role in the development of central nervous system and T cell differentiation by regulating the expression of numerous genes involved in several pathways. Monoallelic defects in the BCL11B gene leading to loss-of-function are associated with a wide spectrum of phenotypes, including neurological disorders with or without immunological features and susceptibility to hematological malignancies. From the genetic point of view, the landscape of BCL11B mutations reported so far does not fully explain the genotype-phenotype correlation. In this review, we sought to compile the phenotypic and genotypic variables associated with previously reported mutations in this gene in order to provide a better understanding of the consequences of deleterious variants. We also highlight the importance of a careful evaluation of the mutation type, its location and the pattern of inheritance of the variants in order to assign the most accurate pathogenicity and actionability of the genetic findings.

The Role of Bcl11 Transcription Factors in Neurodevelopmental Disorders

Neurodevelopmental disorders (NDDs) comprise a diverse group of diseases, including developmental delay, autism spectrum disorder (ASD), intellectual disability (ID), and attention-deficit/hyperactivity disorder (ADHD). NDDs are caused by aberrant brain development due to genetic and environmental factors. To establish specific and curative therapeutic approaches, it is indispensable to gain precise mechanistic insight into the cellular and molecular pathogenesis of NDDs. Mutations of BCL11A and BCL11B, two closely related, ultra-conserved zinc-finger transcription factors, were recently reported to be associated with NDDs, including developmental delay, ASD, and ID, as well as morphogenic defects such as cerebellar hypoplasia. In mice, Bcl11 transcription factors are well known to orchestrate various cellular processes during brain development, for example, neural progenitor cell proliferation, neuronal migration, and the differentiation as well as integration of neurons into functional circuits. Developmental defects observed in both, mice and humans display striking similarities, suggesting Bcl11 knockout mice provide excellent models for analyzing human disease. This review offers a comprehensive overview of the cellular and molecular functions of Bcl11a and b and links experimental research to the corresponding NDDs observed in humans. Moreover, it outlines trajectories for future translational research that may help to better understand the molecular basis of Bcl11-dependent NDDs as well as to conceive disease-specific therapeutic approaches.

Clinico-biological refinement of BCL11B-related disorder and identification of an episignature: A series of 20 unreported individuals

PURPOSE

BCL11B-related disorder (BCL11B-RD) arises from rare genetic variants within the BCL11B gene, resulting in a distinctive clinical spectrum encompassing syndromic neurodevelopmental disorder, with or without intellectual disability, associated with facial features and impaired immune function. This study presents an in-depth clinico-biological analysis of 20 newly reported individuals with BCL11B-RD, coupled with a characterization of genome-wide DNA methylation patterns of this genetic condition.

METHODS

Through an international collaboration, clinical and molecular data from 20 individuals were systematically gathered, and a comparative analysis was conducted between this series and existing literature. We further scrutinized peripheral blood DNA methylation profile of individuals with BCL11B-RD, contrasting them with healthy controls and other neurodevelopmental disorders marked by established episignature.

RESULTS

Our findings unveil rarely documented clinical manifestations, notably including Rubinstein-Taybi-like facial features, craniosynostosis, and autoimmune disorders, all manifesting within the realm of BCL11B-RD. We refine the intricacies of T cell compartment alterations of BCL11B-RD, revealing decreased levels naive CD4+ T cells and recent thymic emigrants while concurrently observing an elevated proportion of effector-memory expressing CD45RA CD8+ T cells (TEMRA). Finally, a distinct DNA methylation episignature exclusive to BCL11B-RD is unveiled.

CONCLUSION

This study serves to enrich our comprehension of the clinico-biological landscape of BCL11B-RD, potentially furnishing a more precise framework for diagnosis and follow-up of individuals carrying pathogenic BCL11B variant. Moreover, the identification of a unique DNA methylation episignature offers a valuable diagnosis tool for BCL11B-RD, thereby facilitating routine clinical practice by empowering physicians to reevaluate variants of uncertain significance within the BCL11B gene.

Genetic diagnostic yield in an 11-year cohort of craniosynostosis patients

Craniosynostosis may present in isolation, 'non-syndromic', or with additional congenital anomalies/neurodevelopmental disorders, 'syndromic'. Clinical focus shifted from confirming classical syndromic cases to offering genetic testing to all craniosynostosis patients. This retrospective study assesses diagnostic yield of molecular testing by investigating prevalences of chromosomal and monogenic (likely) pathogenic variants in an 11-year cohort of 1020 craniosynostosis patients. 502 children underwent genetic testing. Pathogenic variants were identified in 174 patients (35%). Diagnostic yield was significantly higher in syndromic craniosynostosis (62%) than in non-syndromic craniosynostosis (6%). Before whole exome sequencing (WES) emerged, single-gene testing was performed using Sanger sequencing or multiplex ligation-dependent probe amplification (MLPA). Diagnostic yield was 11% and was highest for EFNB1, FGFR2, FGFR3, and IL11RA. Diagnostic yield for copy number variant analysis using microarray was 8%. From 2015 onwards, the WES craniosynostosis panel was implemented, with a yield of 10%. In unsolved, mainly syndromic, cases suspected of a genetic cause, additional WES panels (multiple congenital anomalies (MCA)/intellectual disability (ID)) or open exome analysis were performed with an 18% diagnostic yield. To conclude, microarray and the WES craniosynostosis panel are key to identifying pathogenic variants. in craniosynostosis patients. Given the advances in genetic diagnostics, we should look beyond the scope of the WES craniosynostosis panel and consider extensive genetic diagnostics (e.g. open exome sequencing, whole genome sequencing, RNA sequencing and episignature analysis) if no diagnosis is obtained through microarray and/or WES craniosynostosis panel. If parents are uncomfortable with more extensive diagnostics, MCA or ID panels may be considered.

A novel variant in BCL11B in an individual with neurodevelopmental delay: A case report

BACKGROUND

B-Cell CLL/Lymphoma 11B (BCL11B) is a C2 H2 zinc finger transcription factor that has broad biological functions and is essential for the development of the immune system, neural system, cardiovascular system, dermis, and dentition. Variants of BCL11B have been found in patients with neurodevelopmental disorders and immunodeficiency.

MATERIALS AND METHODS

Whole-exome sequencing (WES) and clinical examinations were performed to identify the etiology of our patient. A variant in the BCL11B gene, NM_138576.4: c.1206delG (p.Phe403Serfs*2) was found and led to frameshift truncation.

RESULTS

We reported a male patient with developmental delay and cerebral palsy who carried the BCL11B variant. The detailed clinical features, such as brain structure and immune detection, were described and reviewed in comparison to previous patients.

CONCLUSIONS

The BCL11B-related neurodevelopmental disorders are rare, and only 17 variants in 25 patients have been found to date. Our report expands the variants spectrum of BCL11B and increases the case of neurodevelopmental abnormalities.

Multisuture craniosynostosis: a case report of unusual presentation of chromosome 14q32 deletion

Multisuture craniosynostosis is associated with a number of syndromes and underlying gene mutations. It is rarely caused by chromosome disorders. For the management, multisuture craniosynostosis raises concerns about abnormal head shape and risks of increased intracranial pressure in affected patients. Calvarial reconstruction to reshape the skull shape and expand the intracranial volume plays an essential role in correcting particular problems. Here, we report a 2-month-old female infant presenting with low birth weight, abnormal head shape, dysmorphic facies and pinnae, hypotonia, and feeding difficulty. Three-dimensional computed tomographic scans revealed left unicoronal and sagittal synostoses. Chromosome microarray analysis revealed de novo chromosome 14q32.12-q32.31 deletion. Among the deleted genes, YY1 and BCL11B are the most likely candidate genes causing craniosynostosis. Some clinical features of the patient are similar to Temple syndrome indicating that the deleted region is paternal in origin. In summary, this is a rare case of chromosome 14q32 deletion with multisuture craniosynostosis. We also report the multidisciplinary management and clinical outcomes after early cranial vault remodelling procedures.

Novel BCL11B truncation variant in a patient with developmental delay, distinctive features, and early craniosynostosis

Intellectual developmental disorder with dysmorphic facies, speech delay, and T-cell abnormalities (MIM # 618092) is a congenital disorder derived from pathogenic variants of the B-cell leukemia/lymphoma 11B gene (BCL11B). Several variants have been reported to date. Here, through comprehensive genomic analysis, a novel BCL11B truncation variant, NM_138576.4(BCL11B_v001): c.2439_2452dup [p.(His818Argfs*31)], was identified in a Japanese male patient with developmental delay, distinctive features, and early craniosynostosis.

Case report: A novel truncating variant of BCL11B associated with rare feature of craniosynostosis and global developmental delay

Craniosynostosis is a premature fusion of cranial sutures, resulting in abnormally shaped skull and brain development disorder. The description of craniosynostosis in patients with BCL11B mutations is rare. Here, we firstly report a 25-month-old Chinese boy with a novel frameshift variant in BCL11B gene. The patient was identified c.2346_2361del by whole-exome sequencing and was confirmed to be de novo by parental Sanger sequencing. This patient presented clinical phenotype of craniosynostosis as well as global developmental delay. He had a small mouth, thin upper lip, arched eyebrows, a long philtrum, midfacial hypoplasia and craniosynostosis. Brain MRI showed brain extracerebral interval and myelination changes, and brain CT with 3D reconstruction showed multi-craniosynostosis. Our study expands the clinical phenotypes of patients with BCL11B gene mutation, and our findings may help guide clinical treatment and family genetic counseling.