Although familial forms of cerebral cavernous malformation are mainly attributed to three CCM genes (KRIT1, CCM2 and PDCD10), no mutation is identified in sporadic cerebral cavernous malformation cases with a unique lesion, indicating additional genes for sporadic cerebral cavernous malformation. To screen the candidate genes, we conducted whole exome sequencing in 31 sporadic cerebral cavernous malformation patients and 32 healthy controls, and identified 5 affected individuals carrying 6 heterozygous deleterious mutations in RNF213 but no RNF213 mutation in healthy individuals. To further confirm RNF213 was associated with cerebral cavernous malformation, we generated rnf213a homozygous knockout zebrafish and found mutation of rnf213a in zebrafish led to a mulberry-like cluster of disordered-flow vascular channels which was reminiscent of human cerebral cavernous malformation. In addition, we revealed kbtbd7 and anxa6 were significantly downregulated due to rnf213a mutation through transcriptomic sequencing and RT-qPCR analysis. Based on the mulberry-like phenotype partly rescued by mRNA of kbtbd7 as well as anxa6, we suggested that rnf213a promoted mulberry-like cluster via downregulation of kbtbd7 and anxa6. Altogether, we firstly demonstrate RNF213is a novel candidate gene for sporadic cerebral cavernous malformation and the mutation of rnf213a is responsible for the mulberry-like cluster in zebrafish.

Background: Balamuthia mandrillaris is a free-living amoebic parasite that primarily causes rare opportunistic infections in immunocompromised hosts. Balamuthia amoebic encephalitis (BAE) is a rare yet severe parasitic infection affecting the central nervous system. It has an extremely low incidence in China but can have a mortality rate as high as 98%. The clinical manifestations of amebic infections are similar to those of bacterial and tuberculous meningitis, lacking specificity, which makes accurate diagnosis challenging in the clinical setting. Case Presentation: A 61-year-old immunocompetent woman experienced worsening headache and a moderate fever over the course of five days, initially treated as a common cold. On 25 February 2025, she exhibited behavioral abnormalities, dysphagia, and a high fever of 40.2 °C, which progressed to a coma. On 26 February, her cranial CT scan revealed multifocal hemorrhagic lesions in the right frontotemporoparietal lobes. The MRI revealed similar lesions with slight enhancement and herniation. She underwent an emergency decompressive craniectomy, yet her condition continued to deteriorate following the surgery. On 27 February, serum targeted next-generation sequencing (tNGS) detected B. mandrillaris. Additionally, metagenomic NGS (mNGS) of the cerebrospinal fluid (CSF) sample confirmed the presence on 28 February. Finally, B. mandrillaris was identified through a brain tissue biopsy on 3 March. However, due to the delayed diagnosis and lack of effective drugs, her condition rapidly deteriorated and became irreversible. Her family ultimately chose to withdraw treatment. Conclusions: This study highlights the application of NGS for early diagnosis of patients with severe CNS infection. Both tNGS and mNGS can be considered for the rapid detection of rare or novel pathogens and for facilitating diagnosis.