Familial cerebral, hepatic, and retinal cavernous angiomas: a new syndrome

KRIT1: A Traffic Warden at the Busy Crossroads Between Redox Signaling and the Pathogenesis of Cerebral Cavernous Malformation Disease

Significance: KRIT1 (Krev interaction trapped 1) is a scaffolding protein that plays a critical role in vascular morphogenesis and homeostasis. Its loss-of-function has been unequivocally associated with the pathogenesis of Cerebral Cavernous Malformation (CCM), a major cerebrovascular disease of genetic origin characterized by defective endothelial cell-cell adhesion and ensuing structural alterations and hyperpermeability in brain capillaries. KRIT1 contributes to the maintenance of endothelial barrier function by stabilizing the integrity of adherens junctions and inhibiting the formation of actin stress fibers. Recent Advances: Among the multiple regulatory mechanisms proposed so far, significant evidence accumulated over the past decade has clearly shown that the role of KRIT1 in the stability of endothelial barriers, including the blood-brain barrier, is largely based on its involvement in the complex machinery governing cellular redox homeostasis and responses to oxidative stress and inflammation. KRIT1 loss-of-function has, indeed, been demonstrated to cause an impairment of major redox-sensitive mechanisms involved in spatiotemporal regulation of cell adhesion and signaling, which ultimately leads to decreased cell-cell junction stability and enhanced sensitivity to oxidative stress and inflammation. Critical Issues: This review explores the redox mechanisms that influence endothelial cell adhesion and barrier function, focusing on the role of KRIT1 in such mechanisms. We propose that this supports a novel model wherein redox signaling forms the common link between the various pathogenetic mechanisms and therapeutic approaches hitherto associated with CCM disease. Future Directions: A comprehensive characterization of the role of KRIT1 in redox control of endothelial barrier physiology and defense against oxy-inflammatory insults will provide valuable insights into the development of precision medicine strategies. Antioxid. Redox Signal. 38, 496-528.

Heterozygous Loss of KRIT1 in Mice Affects Metabolic Functions of the Liver, Promoting Hepatic Oxidative and Glycative Stress

KRIT1 loss-of-function mutations underlie the pathogenesis of Cerebral Cavernous Malformation (CCM), a major vascular disease affecting the central nervous system (CNS). However, KRIT1 is also expressed outside the CNS and modulates key regulators of metabolic and oxy-inflammatory pathways, including the master transcription factor FoxO1, suggesting a widespread functional significance. Herein, we show that the KRIT1/FoxO1 axis is implicated in liver metabolic functions and antioxidative/antiglycative defenses. Indeed, by performing comparative studies in KRIT1 heterozygous (KRIT1^+/−) and wild-type mice, we found that KRIT1 haploinsufficiency resulted in FoxO1 expression/activity downregulation in the liver, and affected hepatic FoxO1-dependent signaling pathways, which are markers of major metabolic processes, including gluconeogenesis, glycolysis, mitochondrial respiration, and glycogen synthesis. Moreover, it caused sustained activation of the master antioxidant transcription factor Nrf2, hepatic accumulation of advanced glycation end-products (AGEs), and abnormal expression/activity of AGE receptors and detoxifying systems. Furthermore, it was associated with an impairment of food intake, systemic glucose disposal, and plasma levels of insulin. Specific molecular alterations detected in the liver of KRIT1^+/− mice were also confirmed in KRIT1 knockout cells. Overall, our findings demonstrated, for the first time, that KRIT1 haploinsufficiency affects glucose homeostasis and liver metabolic and antioxidative/antiglycative functions, thus inspiring future basic and translational studies.

Systemic and CNS manifestations of inherited cerebrovascular malformations

Cerebrovascular malformations occur in both sporadic and inherited patterns. This paper reviews imaging and clinical features of cerebrovascular malformations with a genetic basis. Genetic diseases such as familial cerebral cavernous malformations and hereditary hemorrhagic telangiectasia often have manifestations in bone, skin, eyes, and visceral organs, which should be recognized. Genetic and molecular mechanisms underlying the inherited disorders are becoming better understood, and treatments are likely to follow. An interaction between the intestinal microbiome and formation of cerebral cavernous malformations has emerged, with possible treatment implications. Two-hit mechanisms are involved in these disorders, and additional triggering mechanisms are part of the development of malformations. Hereditary hemorrhagic telangiectasia encompasses a variety of vascular malformations, with widely varying risks, and a more recently recognized association with cortical malformations. Somatic mutations are implicated in the genesis of some sporadic malformations, which means that discoveries related to inherited disorders may aid treatment of sporadic cases. This paper summarizes the current state of knowledge of these conditions, salient features regarding mechanisms of development, and treatment prospects.

Multiple Large-Size Cystic Cerebral Cavernomas

BACKGROUND

Cerebral cavernomas are vascular malformations characterized by networks of abnormally dilated capillaries. They typically present as nodules with mixed signal intensity and a surrounding hemosiderin rim on magnetic resonance imaging. They may occur as multiple lesions in the autosomal-dominant familial form. In rare cases, cavernomas may form cystic masses, mimicking other pathologies.

CASE DESCRIPTION

A 35-year-old man presented with recurrent seizures, aphasia, and gait disturbance with onset at age 14 years. He had previously undergone surgical drainage of multiple cysts across the brain with suspected parasitic infection. On magnetic resonance imaging, 22 cystic lesions were seen across the brain. A large cyst was located in the midline cerebellum, compressing the fourth ventricle. Occipital craniotomy and transvermian dissection allowed total resection of the cyst along with its wall. The postoperative course was uneventful and symptoms progressively improved. Histological analysis revealed cavernoma. Three more surgeries were performed for removal of large supratentorial cavernomas.

CONCLUSIONS

In patients with cystic lesions of the brain, the neurosurgeon should consider the possibility of cavernoma. Total excision along with the cyst wall is crucial for timely diagnosis and therapy.

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.

Familial Cerebral Cavernous Malformations Are Associated with Adrenal Calcifications on CT Scans: An Imaging Biomarker for a Hereditary Cerebrovascular Condition

Purpose To determine if adrenal calcifications seen at computed tomography (CT) are associated with familial cerebral cavernous malformations (fCCMs) in carriers of the CCM1 Common Hispanic Mutation. Materials and Methods This study was approved by the institutional review board. The authors retrospectively reviewed abdominal CT scans in 38 patients with fCCM, 38 unaffected age- and sex-matched control subjects, and 13 patients with sporadic, nonfamilial cerebral cavernous malformation (CCM). The size, number, and laterality of calcifications and the morphologic characteristics of the adrenal gland were recorded. Brain lesion count was recorded from brain magnetic resonance (MR) imaging in patients with fCCM. The prevalence of adrenal calcifications in patients with fCCM was compared with that in unaffected control subjects and those with sporadic CCM by using the Fisher exact test. Additional analyses were performed to determine whether age and brain lesion count were associated with adrenal findings in patients with fCCM. Results Small focal calcifications (SFCs) (≤5 mm) were seen in one or both adrenal glands in 19 of the 38 patients with fCCM (50%), compared with 0 of the 38 unaffected control subjects (P < .001) and 0 of the 13 subjects with sporadic CCM (P = .001). Adrenal calcifications in patients with fCCM were more frequently left sided, with 17 of 19 patients having more SFCs in the left adrenal gland than the right adrenal gland and 50 of the 61 observed SFCs (82%) found in the left adrenal gland. No subjects had SFCs on the right side only. In patients with fCCM, the presence of SFCs showed a positive correlation with age (P < .001) and number of brain lesions (P < .001). Conclusion Adrenal calcifications identified on CT scans are common in patients with fCCM and may be a clinically silent manifestation of disease. ^© RSNA, 2017.

Cerebral cavernous malformations as a disease of vascular permeability: from bench to bedside with caution

Tremendous insight into the molecular and genetic pathogenesis of cerebral cavernous malformations (CCMs) has been gained over the past 2 decades. This includes the identification of 3 distinct genes involved in familial CCMs. Still, a number of unanswered questions regarding the process from gene mutation to vascular malformation remain. It is becoming more evident that the disruption of interendothelial junctions and ensuing vascular hyperpermeability play a principal role. The purpose of this review is to summarize the current understanding of CCM genes, associated proteins, and functional pathways. Promising molecular and genetic therapies targeted at identified molecular aberrations are discussed as well.

Vertebral and spinal cavernous angiomas associated with familial cerebral cavernous malformation

BACKGROUND

Cerebral cavernous malformations are vascular malformations that affect the CNS and have been associated with cutaneous, retinal, and hepatic lesions. Until now, vertebral hemangiomas associated with CCM have been described only in one case. The coexistence of intracranial and spinal cavernous angiomas in familial CCM is extremely rare. In addition to previous studies, the occurrence of spinal, vertebral, and cutaneous cavernous angiomas is now described in different members of a large family with CCM.

CASE DESCRIPTION

Our study reports a previously described family (IFCAS-07) with 12 members affected by autosomal dominant cavernous angiomas: 11 had CCM either alone or associated with hepatic or retinal angiomas, and one had only hepatic angioma. In all 11 members affected by CCM, the mutation of CCM1 gene was detected. During the follow-up, 8 subjects underwent a spinal MRI: 2 because they were symptomatic (thoracic paresthesias, enuresis, back pain) and 6 as a screening examination. Spinal MRI showed in 5 subjects spinal cavernous angiomas either alone or associated with vertebral hemangiomas.

CONCLUSIONS

To our knowledge, this is the largest family reported with different subjects affected by CCM associated with multiple cavernous angiomas throughout (brain and spinal cord) and besides (retina, skin, liver, and vertebral column) the CNS. Comprehensive care of patients with familial CCM includes screening of all the tissues that can be affected and appropriate management by specialists. We emphasize the importance of spinal MRI in the diagnosis of spinal and vertebral cavernous angiomas in all patients affected by familial CCM.

Multiple intracranial cavernous malformations: clinical features and treatment

BACKGROUND

Although patients with MCMs have increasingly been found in clinics, little has been focused on them. Thus, we intended to investigate these patients' clinical presentations, family history, radiological characters, and treatment strategy.

METHODS

A retrospective review of the files and family investigations were conducted for 30 patients with MCMs. All patients underwent MRI examination. Symptomatic patients underwent the surgical treatment with image-guided technique.

RESULTS

There were 19 male and 11 female patients with a total 79 lesions. The common presentations were seizures, hemorrhages, or focal neurological deficits. Nine patients had positive or doubtful family history. The FLAIR sequence of MRI showed the highest sensitivity in the detection of CM lesions. In 27 symptomatic patients with 69 lesions, total removal was achieved in 19 patients with 48 lesions. In the other 8 patients with 21 lesions, 13 lesions were removed. Preoperative symptoms were improved in 21 patients and unchanged in 5. Preoperative neurological deficits temporarily worsened in one, and a new onset of seizure occurred in other one; but both gradually improved during the follow-up period. Among 3 patients with asymptomatic MCMs, one patient had hemorrhage during the follow-up period and underwent surgical operation.

CONCLUSIONS

Because a high frequency of family CM occurs in MCMs, a detailed family investigation is mandatory for each patient with MCM. Selection of higher sensitive MRI sequence would contribute to detection of more CM lesions. Microsurgery assisted with the neuroimaging techniques is the treatment of choice for symptomatic MCMs.

Giant liver hemangioma in three sisters

We describe a patient, in whom giant liver hemangioma (GLH) was found by ultrasound study in screening for hypertension. Two of her sisters also had GLH. One of them had become symptomatic and the hemangioma was successfully removed. The other sisters were carefully watched. Our patient didn't need any intervention in 4 years of follow-up. The pathogenesis of GLH is still unknown. Recent investigations show a role of the TIE receptor/angiopoietin system in vascular malformations. In literature we only found two other reports about a familial occurrence of liver hemangiomas. A genetic defect in familial GLH has not yet been identified.

Hemangiomas hepáticos familiares

Cavernous hemangioma is the most frequent benign hepatic tumor. These tumors are usually small, solitary or multiple, and asymptomatic but they can be large. In the majority of cases, these tumors are sporadic. We describe a family in which six members from three successive generations presented cavernous hepatic hemangiomas. One of the women, who was taking oral contraceptives, presented a giant cavernous hemangioma causing pain in the right hypochondriac region and biochemical abnormalities while the remaining cases were asymptomatic. We found only one study in the literature that reports familial cavernous hepatic hemangioma; a further two studies describe hepatic hemangiomas in members of families with angiomas in other sites. We believe that description of a new family with this disease is of interest. The findings could support autosomal dominant inheritance as the mode of transmission of these tumors, as well as the existence of proliferative factors in these tumors.

The genetics of cerebrovascular malformations

Certain rare familial or congenital syndromes include cerebrovascular malformations among their constellations of abnormalities. In addition, recognition of familial clustering in a subset of patients with cerebrovascular malformations has led to studies investigating the underlying genetic basis for these lesions. Genetic defects have been identified that cause familial cerebral cavernous malformations and hereditary hemorrhagic telangiectasia, a syndrome that features cerebral arteriovenous malformations. In addition to enhancing presymptomatic screening, identification of the responsible genes may result in a better understanding of the pathogenesis of these lesions, and ultimately, in novel treatments.

Pathologic basis of the symptomatic epilepsies in childhood

The epilepsies in childhood are classified as primary (or idiopathic) and secondary (or symptomatic). The primary epilepsies account for two thirds of all childhood epilepsies and are presumed to be genetically determined. In the remaining one third of cases, a neuropathologic lesion can be identified. This paper summarizes the etiologies of the symptomatic epilepsies. They are classified according to the pathologic processes; malformative, metabolic, neoplastic and phakomatoses, hypoxic-ischemic, infectious, and of unknown pathologic process.