PDCD10 gene mutations in multiple cerebral cavernous malformations

Cerebral cavernous malformations - An overview on genetics, clinical aspects and therapeutic strategies

Cerebral cavernous malformations (CCMs) are abnormally packed blood vessels lined with endothelial cells, that do not exhibit intervening tight junctions, lack muscular and elastic layers and are usually surrounded by hemosiderin and gliosis. CCMs may be sporadic or familial autosomal dominant (FCCMs) caused by loss of function mutations in CCM1 (KRIT1), CCM2 (MGC4607), and CCM3 (PDCD10) genes. In the FCCMs, patients have multiple CCMs, different family members are affected, and developmental venous anomalies are absent. CCMs may be asymptomatic or may manifest with focal neurological deficits with or without associated hemorrhage andseizures. Recent studies identify a digenic "triple-hit" mechanism involving the aquisition of three distinct genetic mutations that culminate in phosphatidylinositol-3-kinase (PIK3CA) gain of function, as the basis for rapidly growing and clinically symptomatic CCMs. The pathophysiology of CCMs involves signaling aberrations in the neurovascular unit, including proliferative dysangiogenesis, blood-brain barrier hyperpermeability, inflammation and immune mediated processes, anticoagulant vascular domain, and gut microbiome-driven mechanisms. Clinical trials are investigating potential therapies, magnetic resonance imaging and plasma biomarkers for hemorrhage and CCMs-related epilepsy, as well as different techniques of neuronavigation and neurosonology to guide surgery in order to minimize post-operatory morbidity and mortality. This review addresses the recent data about the natural history, genetics, neuroimaging and therapeutic approaches for CCMs.

Comprehensive CCM3 Mutational Analysis in Two Patients with Syndromic Cerebral Cavernous Malformation

Cerebral cavernous malformation (CCM) is a vascular disease that affects the central nervous system, which familial form is due to autosomal dominant mutations in the genes KRIT1(CCM1), MGC4607(CCM2), and PDCD10(CCM3). Patients affected by the PDCD10 mutations usually have the onset of symptoms at an early age and a more aggressive phenotype. The aim of this study is to investigate the molecular mechanism involved with CCM3 disease pathogenesis. Herein, we report two typical cases of CCM3 phenotype and compare the clinical and neuroradiological findings with five patients with a familial form of KRIT1 or CCM2 mutations and six patients with a sporadic form. In addition, we evaluated the PDCD10 gene expression by qPCR and developed a bioinformatic pipeline to understand the structural changes of mutations. The two CCM3 patients had an early onset of symptoms and a high lesion burden. Furthermore, the sequencing showed that Patient 1 had a frameshift mutation in c.222delT; p.(Asn75Thrfs*14) that leads to lacking the last 124 C-terminal amino acids on its primary structure and Patient 2 had a variant on the splicing site region c.475-2A > G. The mRNA expression was fourfold lower in both patients with PDCD10 mutation. Using in silico analysis, we identify that the frameshift mutation transcript lacks the C-terminal FAT-homology domain compared to the wild-type PDCD10 and preserves the N-terminal dimerization domain. The two patients studied here allow estimating the potential impact of mutations in clinical interpretation as well as support to better understand the mechanism and pathogenesis of CCM3.

Programmed cell death 10 can be used as a potential biomarker for ankylosing spondylitis diagnosis and treatment

STUDY DESIGN

Diagnostic study.

OBJECTIVE

Programmed cell death 10 (PDCD10) is a new versatile molecule involved in signal transduction regulation in angiogenesis and tumors. The potential of using it as a biomarker for the diagnosis of ankylosing spondylitis (AS) is still unknown.

SETTING

University laboratory in Gannan Medical University, China.

METHODS

Expression of PDCD10 was analyzed using clinical samples of patients with AS and Gene Expression Omnibus (GEO) data GDS5231. To explore its function, PDCD10 was upregulated and downregulated in synovial cells. Spearman analysis was used to study the association between PDCD10 and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). The Receiver operating characteristic (ROC) curve was applied to evaluate the sensitivity and specificity of PDCD10.

RESULTS

Expression of PDCD10 was upregulated in patients with AS and it is capable of promoting the calcification of synovial cells. A positive association between PDCD10 and the BASDAI and the mSASSS was observed. The area under the ROC curve (AUC) of PDCD10 was 82% with a 95% confidence interval of [0.772, 0.868].

CONCLUSIONS

PDCD10 is upregulated in patients with AS and it can promote the calcification of synovial cells in vitro. PDCD10 is positively associated with outcome parameters of AS. ROC analysis of PDCD10 suggests that it can be used as a biomarker for the diagnosis and treatment of AS.

Symptomatic and Stenotic Developmental Venous Anomaly with Pontine Capillary Telangiectasia: A Case Report with Genetic Considerations

Stenotic developmental venous anomalies (DVAs) often present with neurological deficits. In addition, cerebral capillary telangiectasia (CCT) coexisting with DVA is rarely encountered, and its pathophysiology, including the underlying genetics, and appropriate management remain uncertain. A 46-year-old man without any medical history of note was referred to our hospital with gradually worsening cerebellar ataxia. Two months after symptom onset, ataxic dysarthria and gait emerged. Brain magnetic resonance imaging showed CCT occupying the pons and left cerebellar peduncle. Subsequent catheter angiography demonstrated a DVA leading from the mass into the cavernous sinus with marked outlet stenosis and flow stagnation. We hypothesized that venous congestion was the source of gradual neurological deterioration and therefore initiated anticoagulation. Symptoms showed mild improvement, and his neurological status has remained stable as of 1 year after symptom onset. Whole-exome sequencing of germline DNA did not reveal any rare variants in genes previously reported as pertinent to vascular malformations. Anticoagulation may be a useful option in patients with non-thrombotic, stenotic DVA for whom neurological status did not improve under expectant management. Genetic analysis of this patient did not reveal any pathogenic mutations, and further investigation of somatic mutations is necessary to elucidate potential genetic causes.

Cas9-Mediated Nanopore Sequencing Enables Precise Characterization of Structural Variants in CCM Genes

Deletions in the CCM1, CCM2, and CCM3 genes are a common cause of familial cerebral cavernous malformations (CCMs). In current molecular genetic laboratories, targeted next-generation sequencing or multiplex ligation-dependent probe amplification are mostly used to identify copy number variants (CNVs). However, both techniques are limited in their ability to specify the breakpoints of CNVs and identify complex structural variants (SVs). To overcome these constraints, we established a targeted Cas9-mediated nanopore sequencing approach for CNV detection with single nucleotide resolution. Using a MinION device, we achieved complete coverage for the CCM genes and determined the exact size of CNVs in positive controls. Long-read sequencing for a CCM1 and CCM2 CNV revealed that the adjacent ANKIB1 and NACAD genes were also partially or completely deleted. In addition, an interchromosomal insertion and an inversion in CCM2 were reliably re-identified by long-read sequencing. The refinement of CNV breakpoints by long-read sequencing enabled fast and inexpensive PCR-based variant confirmation, which is highly desirable to reduce costs in subsequent family analyses. In conclusion, Cas9-mediated nanopore sequencing is a cost-effective and flexible tool for molecular genetic diagnostics which can be easily adapted to various target regions.

The Genetic Architecture of Vascular Anomalies: Current Data and Future Therapeutic Perspectives Correlated with Molecular Mechanisms

Vascular anomalies (VAs) are morphogenesis defects of the vascular system (arteries, capillaries, veins, lymphatic vessels) singularly or in complex combinations, sometimes with a severe impact on the quality of life. The progress made in recent years with the identification of the key molecular pathways (PI3K/AKT/mTOR and RAS/BRAF/MAPK/ERK) and the gene mutations that lead to the appearance of VAs has allowed the deciphering of their complex genetic architecture. Understanding these mechanisms is critical both for the correct definition of the phenotype and classification of VAs, as well as for the initiation of an optimal therapy and the development of new targeted therapies. The purpose of this review is to present in synthesis the current data related to the genetic factors involved in the etiology of VAs, as well as the possible directions for future research. We analyzed the data from the literature related to VAs, using databases (Google Scholar, PubMed, MEDLINE, OMIM, MedGen, Orphanet) and ClinicalTrials.gov. The obtained results revealed that the phenotypic variability of VAs is correlated with genetic heterogeneity. The identification of new genetic factors and the molecular mechanisms in which they intervene, will allow the development of modern therapies that act targeted as a personalized therapy. We emphasize the importance of the geneticist in the diagnosis and treatment of VAs, as part of a multidisciplinary team involved in the management of VAs.

Compendium of causative genes and their encoded proteins for common monogenic disorders

A compendium is presented of inherited monogenic disorders that have a prevalence of >1:20,000 in the human population, along with their causative genes and encoded proteins. "Simple" monogenic diseases are those for which the clinical features are caused by mutations impacting a single gene, usually in a manner that alters the sequence of the encoded protein. Of course, for a given "monogenic disorder", there is sometimes more than one potential disease gene, mutations in any one of which is sufficient to cause phenotypes of that disorder. Disease-causing mutations for monogenic disorders are usually passed on from generation to generation in a Mendelian fashion, and originate from spontaneous (de novo) germline founder mutations. In the past monogenic disorders have often been written off as targets for drug discovery because they sometimes are assumed to be rare disorders, for which the meager projected financial payoff of drug discovery and development has discouraged investment. However, not all monogenic diseases are rare. Here, we report that that currently available data identifies 72 disorders with a prevalence of at least 1 in 20,000 humans. For each, we tabulate the gene(s) for which mutations cause the spectrum of phenotypes associated with that disorder. We also identify the gene and protein that most commonly causes each disease. 34 of these disorders are caused exclusively by mutations in only a single gene and encoded protein.

Description of Two Families with New Mutations in Familial Cerebral Cavernous Malformations Genes

Cerebral cavernous malformations (CCMs) are dilated aberrant leaky capillaries located in the Central Nervous System. Familial CCM is an autosomal dominant inherited disorder related to mutations in KRIT1, Malcavernin or PDCD10. We show two unrelated families presenting familial CCM due to two new mutations in KRIT1 and PDCD10, producing truncated proteins. Clinical phenotype was highly variable among patients from asymptomatic individuals to diplopia, seizures or severe intracranial hemorrhage. PDCD10 patients usually show a more aggressive course and they frequently showed multiple meningiomas. This work provides evidence for the pathogenicity of two new mutations in CCM genes and supports previous findings regarding familial CCM and multiple meningiomas.

Clinical, neuroradiological and genetic findings in a cohort of patients with multiple Cerebral Cavernous Malformations

Cerebral cavernous malformations (CCM) consist of clusters of irregular dilated capillaries and represent the second most common type of vascular malformation affecting the central nervous system. CCM might be asymptomatic or cause cerebral hemorrhage, seizures, recurrent headaches and focal neurologic deficits. Causative mutations underlining CCM have been reported in three genes: KRIT1/CCM1, MGC4607/CCM2 and PDCD10/CCM3. Therapeutic avenues are limited to surgery. Here we present clinical, neuroradiological and molecular findings in a cohort of familial and sporadic CCM patients. Thirty subjects underwent full clinical and radiological assessment. Molecular analysis was performed by direct sequencing and MLPA analysis. Twenty-eight of 30 subjects (93%) experienced one or more typical CCM disturbances with cerebral/spinal hemorrhage being the most common (43%) presenting symptom. A molecular diagnosis was achieved in 87% of cases, with three novel mutations identified. KRIT1/CCM1 patients displayed higher risk of de novo CCMs appearance and bleedings. Magnetic Resonance Imaging (MRI) showed that infratentorial region was more frequently affected in mutated subjects while brainstem was often spared in patients with negative genetic testing.

Genetic syndromes with vascular malformations - update on molecular background and diagnostics

Vascular malformations are present in a great variety of congenital syndromes, either as the predominant or additional feature. They pose a major challenge to the clinician: due to significant phenotype overlap, a precise diagnosis is often difficult to obtain, some of the malformations carry a risk of life threatening complications and, for many entities, treatment is not well established. To facilitate their recognition and aid in differentiation, we present a selection of notable congenital disorders of vascular system development, distinguishing between the heritable germinal and sporadic somatic mutations as their causes. Clinical features, genetic background and comprehensible description of molecular mechanisms is provided for each entity.

Signalling through cerebral cavernous malformation protein networks

Cerebral cavernous malformations (CCMs) are neurovascular abnormalities characterized by thin, leaky blood vessels resulting in lesions that predispose to haemorrhages, stroke, epilepsy and focal neurological deficits. CCMs arise due to loss-of-function mutations in genes encoding one of three CCM complex proteins, KRIT1, CCM2 or CCM3. These widely expressed, multi-functional adaptor proteins can assemble into a CCM protein complex and (either alone or in complex) modulate signalling pathways that influence cell adhesion, cell contractility, cytoskeletal reorganization and gene expression. Recent advances, including analysis of the structures and interactions of CCM proteins, have allowed substantial progress towards understanding the molecular bases for CCM protein function and how their disruption leads to disease. Here, we review current knowledge of CCM protein signalling with a focus on three pathways which have generated the most interest—the RhoA–ROCK, MEKK3–MEK5–ERK5–KLF2/4 and cell junctional signalling pathways—but also consider ICAP1-β1 integrin and cdc42 signalling. We discuss emerging links between these pathways and the processes that drive disease pathology and highlight important open questions—key among them is the role of subcellular localization in the control of CCM protein activity.

Fibronectin rescues aberrant phenotype of endothelial cells lacking either CCM1, CCM2 or CCM3

Loss-of-function variants in CCM1/KRIT1, CCM2, and CCM3/PDCD10 are associated with autosomal dominant cerebral cavernous malformations (CCMs). CRISPR/Cas9-mediated CCM3 inactivation in human endothelial cells (ECs) has been shown to induce profound defects in cell-cell interaction as well as actin cytoskeleton organization. We here show that CCM3 inactivation impairs fibronectin expression and consequently leads to reduced fibers in the extracellular matrix. Despite the complexity and high molecular weight of fibronectin fibrils, our in vitro model allowed us to reveal that fibronectin supplementation restored aberrant spheroid formation as well as altered EC morphology, and suppressed actin stress fiber formation. Yet, fibronectin replacement neither enhanced the stability of tube-like structures nor inhibited the survival advantage of CCM3^-/- ECs. Importantly, CRISPR/Cas9-mediated introduction of biallelic loss-of-function variants into either CCM1 or CCM2 demonstrated that the impaired production of a functional fibronectin matrix is a common feature of CCM1-, CCM2-, and CCM3-deficient ECs.

First interchromosomal insertion in a patient with cerebral and spinal cavernous malformations

Autosomal dominant cerebral cavernous malformations (CCM) are leaky vascular lesions that can cause epileptic seizures and stroke-like symptoms. Germline mutations in either CCM1, CCM2 or CCM3 are found in the majority of patients with multiple CCMs or a positive family history. Recently, the first copy number neutral inversion in CCM2 has been identified by whole genome sequencing in an apparently mutation-negative CCM family. We here asked the question whether further structural genomic rearrangements can be detected within NGS gene panel data of unsolved CCM cases. Hybrid capture NGS data of eight index patients without a pathogenic single nucleotide, indel or copy number variant were analyzed using two bioinformatics pipelines. In a 58-year-old male with multiple CCMs in his brain and spinal cord, we identified a 294 kb insertion within the coding sequence of CCM2. Fine mapping of the breakpoints, molecular cytogenetic studies, and multiplex ligation-dependent probe amplification verified that the structural variation was an inverted unbalanced insertion that originated from 1p12-p11.2. As this rearrangement disrupts exon 6 of CCM2 on 7p13, it was classified as pathogenic. Our study demonstrates that efforts to detect structural variations in known disease genes increase the diagnostic sensitivity of genetic analyses for well-defined Mendelian disorders.

A novel CCM3 mutation associated with cerebral cavernous malformation in a Chinese family

Background:

Cerebral cavernous malformation (CCM), especially the familial form, is a relatively rare congenital and occult vascular disease of the central nervous system. The familial form of CCM has been linked to three different genes: KRIT1/CCM1, MGC4607/CCM2, and PDCD10/CCM3; however, the genetic basis of CCM is not well understood. The PDCD10/CCM3 is the most recent gene to be identified that results in worse clinical symptoms. Early diagnosis and treatment is important for patient prognosis.

Case report:

The proband is a 38-year-old male who has been suffering from weakness in the limbs for 7 months. Investigation of his family history revealed that his mother also suffered from limbs paralysis and had been bedridden for a long time. His older brother suffered from headache for years, whereas his younger brother was asymptomatic. Brain computed tomography analysis of all family members showed multiple high-density shadows. Subsequently, magnetic resonance imaging analysis identified more prominent and similar multiple intracranial lesions in all family members. The lesions were hypo-intense, or showed mixed signs on T1-weighted imaging, and were significantly more intense on T2-weighted imaging. To understand the genetic basis of the disease in the family, DNA sequencing analysis was performed. A novel deletion mutation in the PDCD10/CCM3 gene was identified in the proband and his relatives. The deletion resulted in a frameshift mutation and premature termination of translation of the protein, and potentially caused the disease in this family.

Conclusions:

Our study identified a novel PDCD10/CCM3 heterozygous deletion (c.165delT) associated with CCM. This finding expands the CCM gene mutation profile, which will be beneficial for genetic counseling and clinical therapy.

Low mutational load in pediatric medulloblastoma still translates into neoantigens as targets for specific T-cell immunotherapy

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in childhood and adolescence. Although some patients present with distinct genetic alterations, such as mutated TP53 or MYC amplification, pediatric medulloblastoma is a tumor entity with minimal mutational load and low immunogenicity.

METHODS

We identified tumor-specific mutations using next-generation sequencing of medulloblastoma DNA and RNA derived from primary tumor samples from pediatric patients. Tumor-specific mutations were confirmed using deep sequencing and in silico analyses predicted high binding affinity of the neoantigen-derived peptides to the patients' human leukocyte antigen molecules. Tumor-specific peptides were synthesized and used to induce a de novo T-cell response characterized by interferon gamma and tumor necrosis factor alpha release of CD8⁺ cytotoxic T cells in vitro.

RESULTS

Despite low mutational tumor burden, at least two immunogenic tumor-specific peptides were identified in each patient. T cells showed a balanced CD4/CD8 ratio and mostly effector memory phenotype. Induction of a CD8-specific T-cell response was achieved for the neoepitopes derived from Histidine Ammonia-Lyase (HAL), Neuraminidase 2 (NEU2), Proprotein Convertase Subtilisin (PCSK9), Programmed Cell Death 10 (PDCD10), Supervillin (SVIL) and tRNA Splicing Endonuclease Subunit 54 (TSEN54) variants.

CONCLUSION

Detection of patient-specific, tumor-derived neoantigens confirms that even in tumors with low mutational load a molecular design of targets for specific T-cell immunotherapy is possible. The identified neoantigens may guide future approaches of adoptive T-cell transfer, transgenic T-cell receptor transfer or tumor vaccination.

CCM1/KRIT1 mutation in monozygotic twins of a polyzygotic triplet birth: genetic, clinical and radiological characteristics

Cerebral cavernous malformations are focal vascular lesions of the brain, occurring sporadically or as an autosomal dominant familial form. The genetic background influences not only the clinical course but also patients' consultation and the indication to treat. We here present the rare case of monozygotic male twins of a polyzygotic triplet birth, carrying a CCM1 mutation, inherited from the mother. Both twins showed an identical site and size of a large frontobasal lesion. The genetic segregation and the clinical course in affected family members are presented and discussed.

A novel PDCD10 gene mutation in cerebral cavernous malformations: a case report and review of the literature

Cerebral cavernous malformations (CCMs) are one of the most common types of vascular malformation, which are featured enlarged and irregular small blood vessels. The cavernous cavities are merely composed of a single layer of endothelial cells and lack other support tissues, such as elastic fibers and smooth muscle, which make them elastic. CCMs may develop in sporadic or familial forms with autosomal dominant inheritance. Mutations have been identified in three genes: KRIT1, MGC4607, and PDCD10. Here, we report a typical case of CCMs in a 44-year-old woman associated with a novel mutation in PDCD10 gene. The patient, diagnosed with CCMs, has been suffering from headache for several months. Analyses of the Whole Exome Sequencing revealed a novel disease-associated mutation in the already known disease-associated PDCD10 gene. This mutation consists a nucleotide deletion (c.212delG) within the exon 4, resulting in premature protein termination (p.S71Tfs*18). This novel mutation significantly enriches the spectrum of mutations responsible for CCMs, providing a new evidence for further clarifying the genotype-phenotype correlations in CCMs patients.

First case of neutropenia and thrombocytopenia in the setting of cerebral cavernous malformation 3

Cerebral cavernous malformation 3 (CCM3) is a vascular malformation disorder causing brain slow-flow vascular parenchymal lesions. These lesions are the result of variants in the Programmed Cell Death Protein 10 (PDCD10) gene, located on 3q26.1. We report an 8-month-old patient who was presented with seizures and intracranial abscesses and was found to have a variant of PDCD10 on whole exome sequencing, representing, to our knowledge, the youngest case of CCM3 described in the literature. Her clinical course was complicated by the development of neutropenia, requiring granulocyte colony-stimulating factor, and thrombocytopenia, requiring intermittent platelet transfusions, with later development of B acute lymphoblastic leukemia 2 years after initial presentation. This case represents the first description in the literature of hematologic complications in the setting of CCM3. We hypothesize that these hematological manifestations are the result of alterations in the actin and microtubule cytoskeleton, affecting the process of hematopoiesis in a similar fashion to the documented effect of the PDCD10 variant on neuronal migration.

Biallelic CCM3 mutations cause a clonogenic survival advantage and endothelial cell stiffening

CCM3, originally described as PDCD10, regulates blood‐brain barrier integrity and vascular maturation in vivo. CCM3 loss‐of‐function variants predispose to cerebral cavernous malformations (CCM). Using CRISPR/Cas9 genome editing, we here present a model which mimics complete CCM3 inactivation in cavernous endothelial cells (ECs) of heterozygous mutation carriers. Notably, we established a viral‐ and plasmid‐free crRNA:tracrRNA:Cas9 ribonucleoprotein approach to introduce homozygous or compound heterozygous loss‐of‐function CCM3 variants into human ECs and studied the molecular and functional effects of long‐term CCM3 inactivation. Induction of apoptosis, sprouting, migration, network and spheroid formation were significantly impaired upon prolonged CCM3 deficiency. Real‐time deformability cytometry demonstrated that loss of CCM3 induces profound changes in cell morphology and mechanics: CCM3‐deficient ECs have an increased cell area and elastic modulus. Small RNA profiling disclosed that CCM3 modulates the expression of miRNAs that are associated with endothelial ageing. In conclusion, the use of CRISPR/Cas9 genome editing provides new insight into the consequences of long‐term CCM3 inactivation in human ECs and supports the hypothesis that clonal expansion of CCM3‐deficient dysfunctional ECs contributes to CCM formation.

A novel large deletion in CCM1 gene in a Tunisian family

Familial CCM is a rare entity associated with the mutation of three genes: CCM1 (KRIT1), CCM2 (MGC4607), and CCM3 (PDCD10). We report here the first description of a Tunisian familial CCMs composed of six members. The father and two daughters were affected and symptomatic. The two other kindred were healthy. Surgical treatment was performed in only one affected patient. Molecular analysis of KRIT1, MGC4607 and PDCD10 genes identified a large KRIT1 deletion of the first ten exons. To the best of our knowledge, this large deletion has never been reported before.

Cerebral Cavernous Malformations: An Update on Prevalence, Molecular Genetic Analyses, and Genetic Counselling

Based on the latest gnomAD dataset, the prevalence of symptomatic hereditary cerebral cavernous malformations (CCMs) prone to cause epileptic seizures and stroke-like symptoms was re-evaluated in this review and calculated to be 1:5,400-1:6,200. Furthermore, state-of-the-art molecular genetic analyses of the known CCM loci are described which reach an almost 100% mutation detection rate for familial CCMs if whole genome sequencing is performed for seemingly mutation-negative families. An update on the spectrum of CCM1, CCM2, and CCM3 mutations demonstrates that deep-intronic mutations and submicroscopic copy-number neutral genomic rearrangements are rare. Finally, this review points to current guidelines on genetic counselling, neuroimaging, medical as well as neurosurgical treatment and highlights the formation of active patient organizations in various countries.

First large genomic inversion in familial cerebral cavernous malformation identified by whole genome sequencing

Familial cerebral cavernous malformations (CCMs) predispose to seizures and hemorrhagic stroke. Molecular genetic analyses of CCM1, CCM2, and CCM3 result in a mutation detection rate of up to 98%. However, only whole genome sequencing (WGS) in combination with the Manta algorithm for analyses of structural variants revealed a heterozygous 24 kB inversion including exon 1 of CCM2 in a 12-year-old boy with familial CCMs. Its breakpoints were fine-mapped, and quantitative analysis on RNA confirmed reduced CCM2 expression. Our data expand the spectrum of CCM mutations and indicate that the existence of a fourth CCM disease gene is rather unlikely.

Corrigendum: Cerebral Cavernous Malformations: Review of the Genetic and Protein-Protein Interactions Resulting in Disease Pathogenesis

[This corrects the article on p. 60 in vol. 3, PMID: 27896269.].

Hereditary Multiple Cerebral Cavernous Malformations Associated with Wilson Disease and Multiple Lipomatosis

We report on a patient with 2 Mendelian diseases-symptomatic multiple familial cerebral cavernous malformations (FCCMs) and Wilson disease. Genetic analysis revealed single nucleotide polymorphisms in genes CCM2 and CCM3, associated with cavernous malformations, and homozygote mutation in the ATP7B gene, responsible for Wilson disease. FCCMs were symptomatic in 3 generations. The patient also had multiple lipomatosis, which is suggested to be a familial syndrome. In recent years there has been an increasing amount of publications linking FCCMs with other pathology, predominantly with extracranial and intracranial mesenchymal anomalies. The present study is the description of an unusual association between 2 independent hereditary diseases of confirmed genetic origin-a combination that has not been described previously.

Awad I, Dahlem K, Flemming K, Hart B, Kim H, Jusue-Torres I, Kondziolka D, Lee C, Morrison L, Rigamonti D, Rebeiz T, Tournier-Lasserve E, Waggoner D, Whitehead K. Synopsis of Guidelines for the Clinical Management of Cerebral Cavernous Malformations: Consensus Recommendations Based on Systematic Literature Review by the Angioma Alliance Scientific Advisory Board Clinical Experts Panel

BACKGROUND

Despite many publications about cerebral cavernous malformations (CCMs), controversy remains regarding diagnostic and management strategies.

OBJECTIVE

To develop guidelines for CCM management.

METHODS

The Angioma Alliance ( www.angioma.org ), the patient support group in the United States advocating on behalf of patients and research in CCM, convened a multidisciplinary writing group comprising expert CCM clinicians to help summarize the existing literature related to the clinical care of CCM, focusing on 5 topics: (1) epidemiology and natural history, (2) genetic testing and counseling, (3) diagnostic criteria and radiology standards, (4) neurosurgical considerations, and (5) neurological considerations. The group reviewed literature, rated evidence, developed recommendations, and established consensus, controversies, and knowledge gaps according to a prespecified protocol.

RESULTS

Of 1270 publications published between January 1, 1983 and September 31, 2014, we selected 98 based on methodological criteria, and identified 38 additional recent or relevant publications. Topic authors used these publications to summarize current knowledge and arrive at 23 consensus management recommendations, which we rated by class (size of effect) and level (estimate of certainty) according to the American Heart Association/American Stroke Association criteria. No recommendation was level A (because of the absence of randomized controlled trials), 11 (48%) were level B, and 12 (52%) were level C. Recommendations were class I in 8 (35%), class II in 10 (43%), and class III in 5 (22%).

CONCLUSION

Current evidence supports recommendations for the management of CCM, but their generally low levels and classes mandate further research to better inform clinical practice and update these recommendations. The complete recommendations document, including the criteria for selecting reference citations, a more detailed justification of the respective recommendations, and a summary of controversies and knowledge gaps, was similarly peer reviewed and is available on line www.angioma.org/CCMGuidelines .

A Novel CCM1/KRIT1 Heterozygous Nonsense Mutation (c.1864C>T) Associated with Familial Cerebral Cavernous Malformation: a Genetic Insight from an 8-Year Continuous Observational Study

Cerebral cavernous malformation (CCM) is a congenital vascular abnormality that predominantly affects the central nervous system, but that sometimes encroaches other vital tissues, including the retina, skin, and even liver. The familial form of CCM (FCCM) is considered to be an autosomal dominant disease with incomplete penetrance and variable expression, which is often attributed to mutations in three genes: CCM1, CCM2, and CCM3. We screened a Chinese family diagnosed with FCCM by using Sanger sequencing. A 29-year-old male proband with cutaneous angiomas was pathologically diagnosed but presented with an atypical form of CCM as revealed by magnetic resonance imaging (MRI) findings, prompting further clinical evaluation and genetic analyses of him and his immediate family. We performed continuous observation over an 8-year period using MRI gradient echo imaging and susceptibility-weighted imaging of these individuals. Sanger sequencing of the CCM1, CCM2, and CCM3 genes identified a novel heterozygous nonsense nucleotide transition (c.1864C>T; p.Gln622X) in exon 17 of the CCM1/KRIT1 gene; this mutation was predicted to cause a premature stop codon (TAG) at nucleotides 1864 to 1866 to generate a truncated Krev interaction trapped 1 (Krit1) protein of 621 amino acids. During this long-term observational study, one of the enrolled family members with neurological deficits progressed to a stage indicative of brain surgery. This study provides a new CCM gene mutation profile, which highlights the significance of genetic counseling for individuals suspected of having this condition.

Constitutional de novo and postzygotic mutations in isolated cases of cerebral cavernous malformations

Background

Cerebral cavernous malformations (CCM) are vascular lesions of the central nervous system that can be found in sporadic or autosomal dominantly inherited forms and manifest with headaches, seizures, and hemorrhagic stroke. The precise proportion of de novo mutations in the CCM1,CCM2, and CCM3 genes remains unknown.

Methods

We here present a series of six trios with de novo mutations that have been analyzed by amplicon deep sequencing to differentiate between constitutional and postzygotic mutations.

Results

In one case, allelic ratios clearly indicated mosaicism for a CCM3 splice site mutation found in blood and buccal mucosa of a 2‐year‐old boy with multiple CCMs. The remaining five de novo mutations proved to be constitutional. In addition to three CCM3, two CCM1, and one CCM2 de novo point mutations, a deletion of the entire CCM3 gene was identified in an index case that most likely originated from an early postzygotic event. These are the first high‐level mosaic mutations reported in blood samples of isolated CCM cases.

Conclusion

Our data demonstrate that de novo mutations in CCM1‐3 might be more frequent than previously thought. Furthermore, amplicon deep sequencing is useful to discriminate between patients with constitutional and postzygotic mutations, and thereby improves genetic counseling.

Identification of a Novel Deletion Mutation (c.1780delG) and a Novel Splice-Site Mutation (c.1412-1G>A) in the CCM1/KRIT1 Gene Associated with Familial Cerebral Cavernous Malformation in the Chinese Population

Cerebral cavernous malformation (CCM) is a congenital vascular anomaly predominantly located within the central nervous system. Its familial forms (familial cerebral cavernous malformation (FCCM)), inherited in an autosomal dominant manner with incomplete penetrance, are attributed to mutations in CCM1/KRIT1, CCM2/MGC4607, and CCM3/PDCD10 genes. To date, little is known about the genetic alterations leading to FCCM in the Chinese population. We aimed to investigate the genetic defect of FCCM by DNA sequencing in Chinese families. This study enrolled five Chinese families with FCCM. All index cases underwent surgical treatment and were diagnosed with CCM by pathology; their relatives were diagnosed based on radiological and/or pathological evidence. Genomic DNA was extracted from peripheral blood and amplified using polymerase chain reaction (PCR) for DNA sequencing. The five families comprised a total of 21 affected individuals: 12 of these were symptomatic, and 9 were asymptomatic. Sequence analyses in the index patients disclosed three heterozygous loss-of-function mutations in the CCM1/KRIT1 gene in three families, respectively: a novel deletion mutation (c.1780delG; p.Ala594HisfsX67) in exon 16, a novel splice-site mutation (c.1412-1G>A) in the splice acceptor site in intron 13, and a previously described 4-bp deletion (c.1197_1200delCAAA; p.Gln401ThrfsX10) in exon 12. All of these mutations are predicted to cause a premature termination codon to generate a truncated Krev interaction trapped 1 (Krit1) protein. These mutations segregated in affected relatives. Our findings provided new CCM1 gene mutation profiles, which help to elucidate the pathogenesis of FCCM and will be of great significance in genetic counseling.

Genetics of cerebral cavernous malformations: current status and future prospects

Cerebral cavernous malformations (CCM) are vascular lesions which affect up to 0.5% of the general population, predisposing to headaches, seizures, cerebral hemorrhages and focal neurological deficits. CCM occurs in both sporadic and familial forms; familial cases follow an autosomal-dominant mode of inheritance and are caused by mutations in CCM1 (KRIT1), CCM2 (MGC4607), or CCM3 (PDCD10). Somatic mutations within the three CCM genes have been identified in CCM lesions from both sporadic and familial patients. We reviewed articles published in PubMed in English prior to March 2015 and provide an update on CCM mutations and the screening strategies used to identify them. Further, we summarize the specific clinical features related to CCM genotypes. As 5% to 15% of familial CCM cases remain genetically unexplained, we also discuss future approaches to expand understanding of the genetic architecture of CCM. Finally, we discuss possible genetic modifiers of CCM disease severity and progression. Understanding the genetic architecture of CCM is essential for an earlier diagnosis of the disease, predictive testing of at-risk patients, and design of targeted medical therapies of which there are currently none available.

A Novel MGC4607/CCM2 Gene Mutation Associated with Cerebral Spinal and Cutaneous Cavernous Angiomas

Cerebral cavernous malformations (CCMs) are vascular abnormalities that may cause seizures, headaches, intracerebral hemorrhages, and focal neurological deficits; they can also be clinically silent and occur as a sporadic or an autosomal dominant condition. Three genes have been identified as causing familial CCM: KRIT1/CCM1, MGC4607/CCM2, and PDCD10/CCM3, mapping, respectively, on chromosomes 7q, 7p, and 3q. Here, we report an Italian family affected by CCM due to a MGC4607 gene mutation, on exon 4. All the affected subjects suffered from seizures, and some of them underwent surgery for removal of a cavernous angioma. Brain MRI showed multiple lesions consistent with CCMs in all patients. Spinal and cutaneous cavernous angiomas were present too. This report underlines the need for a careful interdisciplinarity among neurologists, neuroradiologists, neurosurgeons, geneticists, ophthalmologists, and dermatologists for a total evaluation of the different manifestations of familial CCM. This points out that only referral centers are organized to offer a multidisciplinary management of this disease.