Exome-wide Analysis of De Novo and Rare Genetic Variants in Patients With Brain Arteriovenous Malformation

Syndromic craniosynostosis caused by a novel missense variant in MAP4K4: Expanding the genotype-phenotype relationship in RASopathies

RASopathies represent a distinct class of neurodevelopmental syndromes caused by germline variants in the Ras/MAPK pathways. Recently, a novel disease-gene association was implicated in MAPK kinase kinase kinase 4 (MAP4K4), which regulates the upstream signals of the MAPK pathways. However, to our knowledge, only two studies have reported the genotype-phenotype relationships in the MAP4K4-related disorder. This study reports on a Korean boy harboring a novel de novo missense variant in MAP4K4 (NM_001242559:c.569G>T, p.Gly190Val), revealed by trio exome sequencing, and located in the hotspot of the protein kinase domain. The patient exhibited various clinical features, including craniofacial dysmorphism, language delay, congenital heart defects, genitourinary anomalies, and sagittal craniosynostosis. Our study expands the phenotypic association of the MAP4K4-related disorder to include syndromic craniosynostosis, thereby providing further insights into the role of the RAS/MAPK pathways in the development of premature fusion of calvarial sutures.

State of the Art in the Role of Endovascular Embolization in the Management of Brain Arteriovenous Malformations-A Systematic Review

As a significant cause of intracerebral hemorrhages, seizures, and neurological decline, brain arteriovenous malformations (bAVMs) are a rare group of complex vascular lesions with devastating implications for patients' quality of life. Although the concerted effort of the scientific community has improved our understanding of bAVM biology, the exact mechanism continues to be elucidated. Furthermore, to this day, due to the high heterogeneity of bAVMs as well as the lack of objective data brought by the lack of evaluative and comparative studies, there is no clear consensus on the treatment of this life-threatening and dynamic disease. As a consequence, patients often fall short of obtaining the optimal treatment. Endovascular embolization is an inherent part of multidisciplinary bAVM management that can be used in various clinical scenarios, each with different objectives. Well-trained neuro-interventional centers are proficient at curing bAVMs that are smaller than 3 cm; are located superficially in noneloquent areas; and have fewer, larger, and less tortuous feeding arteries. The transvenous approach is an emerging effective and safe technique that potentially offers a chance to cure previously untreatable bAVMs. This review provides the state of the art in all aspects of endovascular embolization in the management of bAVMs.

Remodeling of the Neurovascular Unit Following Cerebral Ischemia and Hemorrhage

Formulated as a group effort of the stroke community, the transforming concept of the neurovascular unit (NVU) depicts the structural and functional relationship between brain cells and the vascular structure. Composed of both neural and vascular elements, the NVU forms the blood-brain barrier that regulates cerebral blood flow to meet the oxygen demand of the brain in normal physiology and maintain brain homeostasis. Conversely, the dysregulation and dysfunction of the NVU is an essential pathological feature that underlies neurological disorders spanning from chronic neurodegeneration to acute cerebrovascular events such as ischemic stroke and cerebral hemorrhage, which were the focus of this review. We also discussed how common vascular risk factors of stroke predispose the NVU to pathological changes. We synthesized existing literature and first provided an overview of the basic structure and function of NVU, followed by knowledge of how these components remodel in response to ischemic stroke and brain hemorrhage. A greater understanding of the NVU dysfunction and remodeling will enable the design of targeted therapies and provide a valuable foundation for relevant research in this area.