A novel CCM1 gene mutation causes cerebral cavernous malformation in a Chinese family

Molecular genetic features and clinical manifestations in Chinese familial cerebral cavernous malformation: from a novel KRIT1/CCM1 mutation (c.1119dupT) to an overall view

Cerebral cavernous malformations (CCMs) are common vascular anomaly diseases in the central nervous system associated with seizures, cerebral microbleeds, or asymptomatic mostly. CCMs can be classified as sporadic or familial, with familial cerebral cavernous malformations (fCCMs) being the autosomal dominant manner with incomplete penetrance. Germline mutations of KRIT1, CCM2, and PDCD10 are associated with the pathogenesis of fCCMs. Till now, little is known about the fCCMs mutation spectrum in the Han Chinese population. In this study, we enrolled a large, aggregated family, 11/26 of the family members were diagnosed with CCMs by pathological or neuroradiological examination, with a high percentage (5/9) of focal spinal cord involvement. Genomic DNA sequencing verified a novel duplication mutation (c.1119dupT, p.L374Sfs*9) in exon 9 of the Krev interaction trapped 1 (KRIT1) gene. The mutation causes a frameshift and is predicted to generate a truncated KRIT1/CCM1 protein of 381 amino acids. All our findings confirm that c.1119dupT mutation of KRIT1 is associated with fCCMs, which enriched the CCM genes' mutational spectrum in the Chinese population and will be beneficial for deep insight into the pathogenesis of Chinese fCCMs. Additionally, with a retrospective study, we analyzed the molecular genetic features of Chinese fCCMs, most of the Chinese fCCMs variants are in the KRIT1 gene, and all these variants result in the functional deletion or insufficiency of the C-terminal FERM domain of the KRIT1 protein.

A Chinese Family With Cerebral Cavernous Malformation Caused by a Frameshift Mutation of the CCM1 Gene: A Case Report and Review of the Literature

Background

Familial cerebral cavernous malformation (FCCM) is a vascular malformation disease closely linked to three identified genes: KRIT1/CCM1, MGC4607/CCM2 and PDCD10/CCM3. Over the past decade, a few cases of cerebral cavernous malformation (CCM) caused by different gene mutations have been reported in Chinese families. Herein, we introduce a Chinese family affected by FCCM due to a kind of KRIT1/CCM1 frameshift mutation. At the same time, a literature review was conducted to identify case reports of familial cerebral cavernous malformation.

Case presentation

The proband in the family in question demonstrated a series of clinical symptoms and features, including headache and bleeding. The proband was hospitalized for headache twice and, both times was examined under suspicion of CCM and received surgical treatment. Magnetic resonance imaging results showed that the proband had multiple intracranial vascular lesions, including on the brain, brainstem, and cerebellum. Genetic test results showed that the classic KRIT1 gene in the proband had a pathogenic mutation. The family members of the proband also showed typical cerebral cavernous malformation when considering clinical manifestations, magnetic resonance imaging findings and genetic test results.

Conclusions

We report a case of Chinese FCCM and its associated symptoms with CCM1-deletion mutations in China. Our findings deepen our understanding of CCM mutations and related phenotypes, the investigation results of this clinical experiment further show that the gene mutation form we reported plays an important role in human FCCM, and this trial investigation is beneficial for genetic counseling for CCM patients.

KRIT1 Gene in Patients with Cerebral Cavernous Malformations: Clinical Features and Molecular Characterization of Novel Variants

Cerebral cavernous malformations (CCMs) are vascular malformations that may result in headaches, seizures, focal neurological deficits, and hemorrhage. CCMs occur sporadically (80%) or in familial form (20%), with autosomal dominant inheritance. Among the three CCM-related genes, mutations in KRIT1 account for 53–65% of familial cases and more than 100 different mutations have been identified so far. In the present work, we describe the clinical, neuroradiological, and genetic findings of sixteen CCM Italian patients, 13 belonging to 4 unrelated families and 3 sporadic cases. Six distinct KRIT1 gene variants, two novel (c.1730+1_1730+3del, c.1664 C>T) and four previously described (c.966G>A, c.1255-1G>A c.1197_1200del, c.1255-1_1256del), were identified, including a possible de novo mutation. All the variants resulted in a premature stop codon. Cerebral 1.5 T magnetic resonance imaging showed multiple CCMs in all the mutation carriers for whom it was available, including sporadic cases. One patient had also cutaneous angiomas. Among the mutation carriers, symptomatic patients constituted 66% and a variable phenotypic expression was observed. Our data confirms phenotypic variability and incomplete penetrance of neurological symptoms in KRIT1-positive families, expands the mutational spectrum of this gene, and highlights how sporadic cases with multiple lesions need an approach similar to individuals with familial CCM.

CCM1 and CCM2 variants in patients with cerebral cavernous malformation in an ethnically Chinese population in Taiwan

Cerebral cavernous malformation (CCM) is a vascular malformation characterized by clustered enlarged capillary-like channels in the central nervous system. The genes harboring variants in patients with CCM include CCM1/Krev interaction trapped-1, CCM2/MGC4607, and CCM3/programmed cell death protein 10. We aimed to identify pathogenic variants in an ethnic Chinese population in Taiwan. We recruited 95 patients with multiple CCMs or a single lesion with a relevant family history. Sanger sequencing was performed for 41 patients. Variants were identified using sequence alignment tools, and the clinical significance of these variants was determined using American College of Medical Genetics and Genomics standards and guidelines. Several pathogenic variants were found in six patients, including three unrelated patients and three affected members of one family. Two novel pathogenic variants leading to early truncation comprised a deletion variant in exon 18 of CCM1 (c.1846delA; p.Glu617LysfsTer44) and an insertion variant in exon 4 of CCM2 (c.401_402insGCCC; p.Ile136AlafsTer4). One novel pathogenic splice site variant was c.485 + 1G > C at the beginning of intron 8 of CCM1. In this study, we identified novel variants related to CCM in an ethnically Chinese population in Taiwan.

Novel KRIT1/CCM1 and MGC4607/CCM2 Gene Variants in Chinese Families With Cerebral Cavernous Malformations

Familial cerebral cavernous malformations (CCMs) are autosomal dominant disorders characterized by hemorrhagic strokes, recurrent headache, epilepsy, and focal neurological deficits. Genetic variants in KRIT1/CCM1, MGC4607/CCM2, and PDCD10/CCM3 genes contribute to CCMs. The clinical information of two Chinese families with CCMs was collected. MRI and video-electroencephalography were performed. Genetic variants of CCM1, CCM2, and CCM3 genes were investigated by exome sequencing. The patients were presented with recurrent epilepsy or headache. Susceptibility-weighted images of brains showed many dark dots, while video-electroencephalography revealed many spikes from multiple brain regions of patients. Exome sequencing revealed a novel CCM1 genetic variant (c.1599_1601TGAdel, p.Asp533del) and a novel CCM2 genetic variant (c.773delA, p.K258fsX34) in Family one and Family two, respectively; cosegregation existed in these two families. The two family members presented typical CCMs symptoms. These two novel genetic variants in CCM1 and CCM2 genes were the causation of CCM in the two Chinese families, and our data enriched the genetic variant spectrum of CCM genes.

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.

A Novel KRIT1/CCM1 Gene Insertion Mutation Associated with Cerebral Cavernous Malformations in a Chinese Family

Familial cerebral cavernous malformation (FCCM) is a vascular malformation disorder that closely associated with three identified genes: KRIT1/CCM1, MGC4607/CCM2, and PDCD10/CCM3. Here, we present a Chinese family affected by FCCM due to a novel KRIT1/CCM1 insertion mutation. The proband was hospitalized for sudden unconsciousness and underwent surgical treatment. The section of lesions showed classical cavernous-dilated vessels without intervening brain parenchyma, and hemosiderin-laden macrophages were accumulated in the surrounding tissue. In addition, magnetic resonance imaging (MRI) showed severe multiple cerebral cavernous malformation (CCM) lesions in cerebrum, brainstem, and cerebellum in other affected subjects. Especially, for the proband's mother, hundreds of lesions were presented, and a few lesions were found in the expanded lateral ventricle (Evans' index =0.33). Moreover, she showed the similar symptoms of hydrocephalus, including headache, dizziness, and diplopia. It was extremely rare in previous reports. To date, the genetic alterations leading to FCCM in Chinese population remain largely unknown. We investigated genetic defects of this family. Sequence analyses disclosed a novel heterozygous insertion mutation (c.1896_1897insT; p.Pro633SerfsTer22) in KRIT1/CCM1. Moreover, our real-time PCR results revealed that the mRNA level of KRIT1/CCM1 were significantly decreased in FCCM subjects (CCM family =0.42 ± 0.20 vs. healthy control =1.01 ± 0.16, P = 0.004). It indicated that this mutation could cause KRIT1/CCM1 functional mRNA deficiency. It may be closely related with the pathogenesis of FCCM. Our findings provided a new gene mutation profile which will be of great significance in early diagnosis and appropriate clinical surveillance of FCCM patients.

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.

Familial cerebral cavernous angiomas: clinical and genetic features in a Chinese family with a frame-shift mutation in the CCM1 gene (krit1)

A few cases of cerebral cavernous malformation (CCM) have been reported in Chinese families with different mutations during the past decade. Herein, we report a case of CCM in a proband in a Chinese family, for whom the mutation type of the CCM remains to be identified. The proband of the family presented a range of clinical symptoms and features that included paralysis, aphasia, multiple lesions in the brain, and cutaneous capillary-venous malformations. PCR was performed to amplify all of the coding exons of the three CCM genes (CCM1, CCM2, and CCM3) in the proband and revealed a heterozygous T deletion in exon 15 (c.1542delT) of CCM1 gene. Targeted mutation analysis in family members demonstrated that this mutation segregated with the disease in the family. This is the first report of a heterozygous CCM1 deletion mutation. Our findings provide a new CCM gene mutation profile in a Chinese family which will be of significance in genetic counseling for CCM.

Varying clinical presentations of familial cerebral cavernous malformations (CCMs) and spinal cord cavernous malformations (SCCMs)

We present a family afflicted by both extensive cerebral cavernous malformations (CCMs) and spinal cord cavernous malformations (SCCMs). These may be inherited in an autosomal dominant pattern or occur sporadically. The presentation varies and may include a multitude of clinical symptoms separated in time and space. Cavernous malformations should be considered in the differential diagnosis of such entities as stroke, headache, multiple sclerosis, and new-onset seizures after an intraparenchymal hemorrhage.

Huashan Hospital affiliated to Fudan University: spanning a century of history

Established in 1907, Huashan Hospital affiliated to Fudan University represents in microcosm the growth of modern Chinese medical science and shows its course of development. Over the past 103 years, the hospital has grown from a staff of a dozen to 3103 staff members, covering an area of 37,396 m(2) with 1216 hospital beds. Huashan Hospital has grown into one of the best-known hospitals in China with multiple world-renowned disciplines, including neurosurgery, hand surgery, dermatology, and infectious disease.