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

Familial cerebral cavernous malformations (CCMs) are characterized by an autosomal dominant transmission with incomplete penetrance. We have previously reported a 1292delAT mutation in the CCM1 gene in a Chinese family with CCM. Here we report a novel deletion of CCM1 that correlates strongly with CCM formation in another family. Ten affected family members were observed among the 25 participants, and multiple CCM lesions were detected in seven individuals. Nucleotide sequencing analysis in the index patient and other affected members showed a CAAA deletion in exon 12 at nucleotide (NT) 1197. We predict this deletion produces a premature stop code (TGA) at NT 1228, resulting in a truncated protein of 409 amino acids.     

CCM3 interacts with CCM2 indicating common pathogenesis for cerebral cavernous malformations

Individuals carrying a mutation in one of the three cerebral cavernous malformation genes (CCM1/KRIT1, CCM2, CCM3) cannot be clinically distinguished, raising the possibility that they act within common molecular pathways. In this study, we demonstrate that CCM3 (PDCD10) coprecipitates and colocalizes with CCM2. We also show that CCM3 directly binds to serine/threonine kinase 25 (STK25, YSK1, SOK1) and the phosphatase domain of Fas-associated phosphatase-1 (FAP-1, PTPN13, PTP-Bas, PTP-BL). CCM3 is phosphorylated by STK25 but not by its other Yeast-Two hybrid interactor STK24, whereas the C-terminal catalytic domain of FAP-1 dephosphorylates CCM3. Finally, our experiments reveal that STK25 forms a protein complex with CCM2. Thus, our data link two proteins of unknown function, CCM3 and STK25, with CCM2, which is part of signaling pathways essential for vascular development and CCM pathogenesis.     

Exome sequencing identifies Laing distal myopathy MYH7 mutation in a Roma family previously diagnosed with distal neuronopathy

We describe a Hungarian Roma family, originally investigated for autosomal dominant distal muscular atrophy. The mother started toe walking at 3 years and lost ambulation at age 27. Her three daughters presented with early steppage gait and showed variable progression. Muscle biopsies were nonspecific showing myogenic lesions in the mother and lesions resembling neurogenic atrophy in the two siblings. To identify the causative abnormality whole exome sequencing was performed in two affected girls and their unaffected father, unexpectedly revealing the MYH7 mutation c.4849_4851delAAG (p.K1617del) in both girls, reported to be causative for Laing distal myopathy. Sanger sequencing confirmed the mutation in the affected mother and third affected daughter. In line with variable severity in Laing distal myopathy our patients presented a more severe phenotype. Our case is the first demonstration of Laing distal myopathy in the Roma and the successful use of whole exome sequencing in obtaining a definitive diagnosis in ambiguous cases.     

Exome sequencing identifies a DNAJB6 mutation in a family with dominantly-inherited limb-girdle muscular dystrophy

Limb-girdle muscular dystrophy primarily affects the muscles of the hips and shoulders (the “limb-girdle” muscles), although it is a heterogeneous disorder that can present with varying symptoms. There is currently no cure. We sought to identify the genetic basis of limb-girdle muscular dystrophy type 1 in an American family of Northern European descent using exome sequencing. Exome sequencing was performed on DNA samples from two affected siblings and one unaffected sibling and resulted in the identification of eleven candidate mutations that co-segregated with the disease. Notably, this list included a previously reported mutation in DNAJB6, p.Phe89Ile, which was recently identified as a cause of limb-girdle muscular dystrophy type 1D. Additional family members were Sanger sequenced and the mutation in DNAJB6 was only found in affected individuals. Subsequent haplotype analysis indicated that this DNAJB6 p.Phe89Ile mutation likely arose independently of the previously reported mutation. Since other published mutations are located close by in the G/F domain of DNAJB6, this suggests that the area may represent a mutational hotspot. Exome sequencing provided an unbiased and effective method for identifying the genetic etiology of limb-girdle muscular dystrophy type 1 in a previously genetically uncharacterized family. This work further confirms the causative role of DNAJB6 mutations in limb-girdle muscular dystrophy type 1D.     

Functional outcome after initial and multiple intracerebral hemorrhages in children with cerebral cavernous malformations

Background and purpose

We aimed to assess the course and predictors of functional outcome after single and multiple intracerebral hemorrhage (ICH) in pediatric patients with cerebral cavernous malformations (CCMs) and to conduct a risk assessment of a third bleed during the first follow-up year after second ICH.

Methods

We included patients aged ≤18 years with complete baseline characteristics, a magnetic resonance imaging dataset, ≥1 CCM-related ICH and ≥1 follow-up examination, who were treated between 2003 and 2021. Neurological functional status was obtained using modified Rankin Scale scores at diagnosis, before and after each ICH, and at last follow-up. Kaplan–Meier analysis was performed to determine the cumulative 1-year risk of third ICH.

Results

A total of 55 pediatric patients (median [interquartile range] age 12 [11] years) were analyzed. Univariate analysis identified brainstem cavernous malformation (BSCM; p = 0.019) as a statistically significant predictor for unfavorable outcome after second ICH. Outcome after second ICH was significantly worse in 12 patients (42.9%; p = 0.030) than after first ICH and in five patients (55.6%; p = 0.038) after a third ICH compared to a second ICH. Cumulative 12-month risk of rebleeding during the first year after a second ICH was 10.7% (95% confidence interval 2.8%–29.37%).

Conclusions

Pediatric patients with a BSCM have a higher risk of worse outcome after second ICH. Functional outcome improves over time after an ICH but worsens following each ICH compared to baseline or previous ICH. Second bleed was associated with neurological deterioration compared to initial ICH, and this deteriorated further after a third ICH.     

Exome sequencing identifies a novel SMCHD1 mutation in facioscapulohumeral muscular dystrophy 2

FSHD2 is a rare form of facioscapulohumeral muscular dystrophy (FSHD) characterized by the absence of a contraction in the D4Z4 macrosatellite repeat region on chromosome 4q35 that is the hallmark of FSHD1. However, hypomethylation of this region is common to both subtypes. Recently, mutations in SMCHD1 combined with a permissive 4q35 allele were reported to cause FSHD2. We identified a novel p.Lys275del SMCHD1 mutation in a family affected with FSHD2 using whole-exome sequencing and linkage analysis. This mutation alters a highly conserved amino acid in the ATPase domain of SMCHD1. Subject III-11 is a male who developed asymmetrical muscle weakness characteristic of FSHD at 13 years. Physical examination revealed marked bilateral atrophy at biceps brachii, bilateral scapular winging, some asymmetrical weakness at tibialis anterior and peroneal muscles, and mild lower facial weakness. Biopsy of biceps brachii in subject II-5, the father of III-11, demonstrated lobulated fibers and dystrophic changes. Endomysial and perivascular inflammation was found, which has been reported in FSHD1 but not FSHD2. Given the previous report of SMCHD1 mutations in FSHD2 and the clinical presentations consistent with the FSHD phenotype, we conclude that the SMCHD1 mutation is the likely cause of the disease in this family.     

散发性颅内海绵状血管畸形CCM1基因新突变位点

BACKGROUND： A cerebral cavernous malformation-1 （CCM1） gene mutation might result in functional loss of KREV interaction trapped-1 （KRIT1）, which is related to onset of cavernous malformations （CM）. However, data addressing sporadic CM in Chinese patients remains limited to date. OBJECTIVE： To analyze CCM1 mutation of Chinese patients with sporadic intracranial CM. DESIGN, TIME AND SETTING： Genetics experiment was performed in the Department of Neurosurgery, Huashan Hospital Affiliated to Fudan University between January 2004 and December 2005. PARTICIPANTS： Ninety patients with sporadic CM served as the CM group, and 30 healthy subjects were considered to be the control group. METHODS： Peripheral blood was collected from patients with CM and from control group subjects Genomic DNA was extracted, and exons 8, 9, 11, 12, 13, 15, 16, 17, and 18, as well as the related introns, were amplified using polymerase chain reaction. DNA sequences were compared with GeneBank. MAIN OUTCOME MEASURES： Abnormal mutable site of CCM1 gene in the two groups. RESULTS： Four exclusive mutations of CCM1 were detected in the CM group, with a sporadic CM mutational rate of 32% （6/19）. Of the four exclusive mutations, there was one missense mutation [exon 12, 1172C→T （S391 F）], one insertion mutation [exon 8, 704insT （K246stop）], one intervening sequence mutation （IVS12-4C→T）, and one synonymous mutation （exon 17, 1875C→T）. With the exception of 1875C→T, all mutations detected in the CM group led to functional changes of the KRIT1 protein, which was encoded by the CCM1 gene. Gene mutations were not detected in the control group. CONCLUSION： Four exclusive mutations of the CCM1 gene were determined in Chinese patients with sporadic CM, which led to functional changes or loss of the encoding KRIT1 protein. KRIT1 protein is considered to be the genetic basis of CM occurrence.     

Modifiable vascular risk factors in patients with cerebral and spinal cavernous malformations: a complete 10-year follow-up study

Background and purpose

The aim was to investigate the effect of modifiable vascular risk factors on the risk of first and recurrent bleeding for patients with a cavernous malformation (CM) of the central nervous system (CNS) over a 10-year period.

Methods

A retrospective review of our CM institutional database was performed spanning from 2003 to 2021. The inclusion criteria were non-missing serial magnetic resonance imaging studies and clinical baseline metrics such as vascular risk factors. The exclusion criteria were patients who underwent surgical CM removal and patients with less than a decade of follow-up. Kaplan–Meier and Cox regression analyses were performed to determine the cumulative risk (10 years) of hemorrhage.

Results

Eighty-nine patients with a CM of the CNS were included. Our results showed a non-significant increased risk of hemorrhage during 10 years of follow-up in patients using nicotine (hazard ratio 2.11, 95% confidence interval 0.86–5.21) and in patients with diabetes (hazard ratio 3.25, 95% confidence interval 0.71–14.81). For the presence of modifiable vascular risk factors at study baseline different cumulative 10-year risks of bleeding were observed: arterial hypertension 42.9% (18.8%–70.4%); diabetes 66.7% (12.5%–98.2%); hyperlipidemia 30% (8.1%–64.6%); active nicotine abuse 50% (24.1%–76%); and obesity 22.2% (4%–59.8%). Overall cumulative (10-year) hemorrhage risk was 30.3% (21.3%–41.1%).

Conclusions

The probability of hemorrhage in untreated CNS CM patients increases progressively within a decade of follow-up. None of the modifiable vascular risk factors showed strong indication for an influence on hemorrhage risk, but our findings may suggest a more aggressive course in patients with active nicotine abuse or suffering from diabetes.     

Familial cerebral cavernous malformation: report of a further Italian family

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 may 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. This is a report on an Italian family affected by CCM due to a KRIT1 gene mutation on exon 13. The mother suffered from a cerebellar hematoma and was severely disabled; one son had suffered from intractable seizures and underwent surgery for removal of a cavernous angioma, while another son was asymptomatic. Brain MRI showed CCMs in all patients. This report underlines that a familial form of CCM could be suspected when a patient presents with multiple CCMs; neurologists and neurosurgeons should be aware that genetic testing for these forms is available.     

Linkage analysis and exome sequencing identify a novel mutation in KCTD7 in patients with progressive myoclonus epilepsy with ataxia

Epilepsy affects approximately 1% of the world's population. Genetic factors and acquired etiologies, as well as a range of environmental triggers, together contribute to epileptogenesis. We have identified a family with three daughters affected with progressive myoclonus epilepsy with ataxia. Clinical details of the onset and progression of the neurologic presentation, epileptic seizures, and the natural history of progression over a 10‐year period are described. Using autozygosity genetic mapping, we identified a high likelihood homozygous region on chromosome 7p12.1‐7q11.22. We subsequently applied whole‐exome sequencing and employed a rare variant prioritization analysis within the homozygous region. We identified p.Tyr276Cys in the potassium channel tetramerization domain–containing seven gene, KCTD7, which is expressed predominantly in the brain. Mutations in this gene have been implicated previously in epileptic phenotypes due to disturbances in potassium channel conductance. Pathogenicity of the mutation was supported by bioinformatic predictive analyses and variant cosegregation within the family. Further biologic validation is necessary to fully characterize the pathogenic mechanisms that explain the phenotypic causes of epilepsy with ataxia in these patients.     

Congenital disorder of glycosylation type 1T with a novel truncated homozygous mutation in PGM1 gene and literature review

The congenital disorders of glycosylation are a group of clinically and biochemically heterogeneous diseases characterized by multisystem involvement due to glycosylation defect of protein and lipid. Here we report a 49-year-old man with exercise-induced fatigue and pain of muscle, tachypnea, cleft palate and bifid uvula. Exercise induced elevation of serum creatine kinase (CK), ammonia and lactic acid was recorded. The abnormal levels of myoglobin, CK-MB and LDH as well as S-T elevation in electrocardiogram were observed in repeated hospitalization recordings. Electromyography showed myopathic damage. Repetitive nerve stimulation test of low rates showed decrement in the left deltoid muscle. He was identified with a novel homozygous frameshift variant in Phosphoglucomutase type 1 gene (c.405delT p.N135Kfs*9) by whole exome sequencing. Muscle biopsy exhibited minimal variation in fiber size without abnormal glycogen accumulation. Compared with controls’, the patient's sample showed no signal at ～61?kDa using N- or C-terminus antibody of Phosphoglucomutase type 1 in western blotting. A signal at ～20?kDa was detected in patient using N-terminus antibody. Immunofluorescence revealed trace expression of C-terminus and a much lower expression of N-terminus on the sarcolemma than normal. Our findings indicate that c.405delT encodes a truncated protein with abnormal distribution and expression in skeletal muscle. In conclusion, genes associated with congenital disorders of glycosylation should be analyzed in patients with maxillofacial dysplasia, exertional weakness, cardiac involvement and exercise-induced-ammoniemia, without glycogen storage in skeletal muscle.     

A novel mutation in NF1 is associated with diverse intra-familial phenotypic variation and astrocytoma in a Chinese family

Neurofibromatosis type 1 (NF1) is a dysregulated neurocutaneous disorder, characterized by neurofibromas and café-au-lait spots. NF1 is caused by mutations in the NF1 gene, encoding neurofibromin. Here, we present a clinical molecular study of a three-generation Chinese family with NF1. The proband was a male patient who showed café-au-lait spots and multiple subcutaneous neurofibromas over the whole body, but his siblings only had regional lesions. The man’s daughter presented with severe headache and vomiting. Neurological examination revealed an intracranial space occupying lesion. Surgery was undertaken and the histopathological examination showed a grade I-II astrocytoma. Next-Generation sequencing (Illumina HiSeq2500 Analyzers; Illumina, San Diego, CA, USA) and Sanger sequencing (ABI PRISM 3730 automated sequencer; Applied Biosystems, Foster City, CA, USA) identified the c.227delA mutation in the NF1 gene in the man. The mutation is co-segregated with the disease phenotypes among the affected members of this family and was absent in 100 healthy controls. This novel mutation results in a frameshift (p.Asn78IlefsX7) as well as truncation of neurofibromin by formation of a premature stop codon. Our results not only extended the mutational and phenotypic spectra of the gene and the disease, but also highlight the importance of the other genetic or environmental factors in the development and severity of the disease.     

Nemaline body myopathy caused by a novel mutation in troponin T1 (TNNT1)

Introduction: Nemaline myopathy is a rare disorder characterized by skeletal muscle weakness of varying severity and onset, with the presence of nemaline rods on muscle biopsy. Congenital nemaline body myopathy due to mutations in TNNT1 has hitherto only been described as a result of a single founder mutation in patients of Amish origin and in 2 other individuals with different recessive mutations. Methods: Autozygosity mapping and whole exome sequencing were applied after we identified 9 Palestinian patients from 7 unrelated families who have nemaline myopathy. Results: All patients were homozygous for a novel complex rearrangement of the TNNT1 gene (c.574_577delinsTAGTGCTGT | NM_003283) leading to C‐terminal truncation of the protein (p.L203* | NP_003274.3). Their clinical course was remarkable for early respiratory failure and striking stiffness of the cervical spine. Conclusions: This report exemplifies the utility of combining autozygosity mapping and whole exome sequencing and expands the phenotype associated with TNNT1 mutations. Muscle Nerve 53 : 564–569, 2016     

Identification of a novel KRIT1 mutation in an Italian family with cerebral cavernous malformation by the protein truncation test

Familial cerebral cavernous malformation (CCM) exhibits autosomal dominant inheritance and is characterized by vascular disorders of the brain, which can lead to seizures, focal neurological deficits, hemorrhagic stroke, and migraine. Three CCM loci have been mapped, but the gene for only one locus--KRIT1 coding for Krev-1/rap1 interaction trapped 1 (KRIT1) protein, which is responsible for more than 40% of familial cases--has been identified. To date, a total of 72 mutations have been described, with one founder effect in the Mexican/Hispanic community. We report the case of an Italian family with CCM that has a novel KRIT1 gene mutation leading to a truncated KRIT1 protein. The protein truncation test (PTT) has been used as a rapid method of identifying germline mutations in the KRIT1 gene.     

Whole‐exome sequencing in an individual with severe global developmental delay and intractable epilepsy identifies a novel,de novo GRIN2A mutation

We present a 4‐year‐old girl with profound global developmental delay and refractory epilepsy characterized by multiple seizure types (partial complex with secondary generalization, tonic, myoclonic, and atypical absence). Her seizure semiology did not fit within a specific epileptic syndrome. Despite a broad metabolic and genetic workup, a diagnosis was not forthcoming. Whole‐exome sequencing with a trio analysis (affected child compared to unaffected parents) was performed and identified a novel de novo missense mutation in GRIN2A, c.2449A>G, p.Met817Val, as the likely cause of the refractory epilepsy and global developmental delay. GRIN2A encodes a subunit of N‐methyl‐d ‐aspartate (NMDA) receptor that mediates excitatory transmission in the central nervous system. A significant reduction in the frequency and the duration of her seizures was observed after the addition of topiramate over a 10‐month period. Further prospective studies in additional patients with mutations in GRIN2A will be required to optimize seizure management for this rare disorder. This report expands the current phenotype associated with GRIN2A mutations. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here .