GNAQ R183Q somatic mutation contributes to aberrant arteriovenous specification in Sturge-Weber syndrome through Notch signaling

Episcleral vasculature malformation is a significant feature of Sturge-Weber syndrome (SWS) secondary glaucoma, the density and diameter of which are correlated with increased intraocular pressure. We previously reported that the GNAQ R183Q somatic mutation was located in the SWS episclera. However, the mechanism by which GNAQ R183Q leads to episcleral vascular malformation remains poorly understood. In this study, we investigated the correlation between GNAQ R183Q and episcleral vascular malformation via surgical specimens, human umbilical vein endothelial cells (HUVECs), and the HUVEC cell line EA.hy926. Our findings demonstrated a positive correlation between episcleral vessel diameter and the frequency of the GNAQ R183Q variant. Furthermore, the upregulation of genes from the Notch signaling pathway and abnormal coexpression of the arterial marker EphrinB2 and venous marker EphB4 were demonstrated in the scleral vasculature of SWS. Analysis of HUVECs overexpressing GNAQ R183Q in vitro confirmed the upregulation of Notch signaling and arterial markers. In addition, knocking down of Notch1 diminished the upregulation of arterial markers induced by GNAQ R183Q. Our findings strongly suggest that GNAQ R183Q leads to malformed episcleral vasculatures through Notch-induced aberrant arteriovenous specification. These insights into the molecular basis of episcleral vascular malformation will provide new pathways for the development of effective treatments for SWS secondary glaucoma.

Developmental expression of the Sturge-Weber syndrome-associated genetic mutation in Gnaq: a formal test of Happle's paradominant inheritance hypothesis

Sturge-Weber Syndrome (SWS) is a sporadic (non-inherited) syndrome characterized by capillary vascular malformations in the facial skin, leptomeninges, or the choroid. A hallmark feature is the mosaic nature of the phenotype. SWS is caused by a somatic mosaic mutation in the GNAQ gene (p.R183Q), leading to activation of the G protein, Gαq. Decades ago, Rudolf Happle hypothesized SWS as an example of "paradominant inheritance", that is, a "lethal gene (mutation) surviving by mosaicism". He predicted that the "presence of the mutation in the zygote will lead to death of the embryo at an early stage of development". We have created a mouse model for SWS using gene targeting to conditionally express the GNAQ p.R183Q mutation. We have employed two different Cre-drivers to examine the phenotypic effects of expression of this mutation at different levels and stages of development. As predicted by Happle, global, ubiquitous expression of this mutation in the blastocyst stage results in 100% embryonic death. The majority of these developing embryos show vascular defects consistent with the human vascular phenotype. By contrast, global but mosaic expression of the mutation enables a fraction of the embryos to survive, but those that survive to birth and beyond do not exhibit obvious vascular defects. These data validate Happle's paradominant inheritance hypothesis for SWS and suggest the requirement of a tight temporal and developmental window of mutation expression for the generation of the vascular phenotype. Furthermore, these engineered murine alleles provide the template for the development of a mouse model of SWS that acquires the somatic mutation during embryonic development, but permits the embryo to progress to live birth and beyond, so that postnatal phenotypes can also be investigated. These mice could then also be employed in pre-clinical studies of novel therapies.

Updates on Sturge-Weber Syndrome

Sturge-Weber syndrome (SWS) is a rare, noninherited neurovascular disorder characterized by abnormal vasculature in the brain, skin, and eye. Patients with SWS characteristically have facial capillary malformation, also known as port-wine birthmark, a leptomeningeal vascular malformation seen on contrast-enhanced magnetic resonance imaging images, abnormal blood vessels in the eye, and glaucoma. Patients with SWS have impaired perfusion to the brain and are at high risk of venous stroke and stroke-like episodes, seizures, and both motor and cognitive difficulties. While the activating R183Q GNAQ somatic mutation is the most common somatic mutation underlying SWS, recent research also implicates that GNA11 and GNB2 somatic mutations are related to SWS. Recent retrospective studies suggest the use of low-dose aspirin and vitamin D in treatment for SWS and prospective drug trials have supported the usefulness of cannabidiol and Sirolimus. Presymptomatic treatment with low-dose aspirin and antiepileptic drugs shows promising results in delaying seizure onset in some patients. This review focuses on the latest progress in the field of research for Sturge-Weber syndrome and highlights directions for future research.

Endothelial GNAQ p.R183Q Increases ANGPT2 (Angiopoietin-2) and Drives Formation of Enlarged Blood Vessels

OBJECTIVE

Capillary malformation (CM) occurs sporadically and is associated with Sturge-Weber syndrome. The somatic mosaic mutation in GNAQ (c.548G>A, p.R183Q) is enriched in endothelial cells (ECs) in skin CM and Sturge-Weber syndrome brain CM. Our goal was to investigate how the mutant Gαq (G-protein αq subunit) alters EC signaling and disrupts capillary morphogenesis. Approach and Results: We used lentiviral constructs to express p.R183Q or wild-type GNAQ in normal human endothelial colony forming cells (EC-R183Q and EC-WT, respectively). EC-R183Q constitutively activated PLC (phospholipase C) β3, a downstream effector of Gαq. Activated PLCβ3 was also detected in human CM tissue sections. Bulk RNA sequencing analyses of mutant versus wild-type EC indicated constitutive activation of PKC (protein kinase C), NF-κB (nuclear factor kappa B) and calcineurin signaling in EC-R183Q. Increased expression of downstream targets in these pathways, ANGPT2 (angiopoietin-2) and DSCR (Down syndrome critical region protein) 1.4 were confirmed by quantitative PCR and immunostaining of human CM tissue sections. The Gαq inhibitor YM-254890 as well as siRNA targeted to PLCβ3 reduced mRNA expression levels of these targets in EC-R183Q while the pan-PKC inhibitor AEB071 reduced ANGPT2 but not DSCR1.4. EC-R183Q formed enlarged blood vessels in mice, reminiscent of those found in human CM. shRNA knockdown of ANGPT2 in EC-R183Q normalized the enlarged vessels to sizes comparable those formed by EC-WT.

CONCLUSIONS

Gαq-R183Q, when expressed in ECs, establishes constitutively active PLCβ3 signaling that leads to increased ANGPT2 and a proangiogenic, proinflammatory phenotype. EC-R183Q are sufficient to form enlarged CM-like vessels in mice, and suppression of ANGPT2 prevents the enlargement. Our study provides the first evidence that endothelial Gαq-R183Q is causative for CM and identifies ANGPT2 as a contributor to CM vascular phenotype.

Pathogenic postzygotic mosaicism in the tyrosine receptor kinase pathway: potential unidentified human disease hidden away in a few cells

Mutations occurring during embryonic development affect only a subset of cells resulting in two or more distinct cell populations that are present at different levels, also known as postzygotic mosaicism (PZM). Although PZM is a common biological phenomenon, it is often overlooked as a source of disease due to the challenges associated with its detection and characterization, especially for very low-frequency variants. Moreover, PZM can cause a different phenotype compared to constitutional mutations. Especially, lethal mutations in receptor tyrosine kinase (RTK) pathway genes, which exist only in a mosaic state, can have completely new clinical manifestations and can look very different from the associated monogenic disorder. However, some key questions are still not addressed, such as the level of mosaicism resulting in a pathogenic phenotype and how the clinical outcome changes with the development and age. Addressing these questions is not trivial as we require methods with the sensitivity to capture some of these variants hidden away in very few cells. Recent ultra-accurate deep-sequencing approaches can now identify these low-level mosaics and will be central to understand systemic and local effects of mosaicism in the RTK pathway. The main focus of this review is to highlight the importance of low-level mosaics and the need to include their detection in studies of genomic variation associated with disease.

Overgrowth syndromes and new therapies

Overgrowth syndromes represent a diverse group of disorders with overlapping features. Interdisciplinary management by a team of experts in vascular anomalies is crucial for establishing the correct diagnosis and optimizing outcomes for these patients. Unique management considerations include increased risk for thrombosis and in some cases, cancer. In recent years, research has demonstrated that these disorders are primarily caused by somatic mutations in growth pathways, particularly the PI3K-mTOR pathway. This improved understanding had led to promising new therapies for this group of patients.

Computational analysis for GNAQ mutations: New insights on the molecular etiology of Sturge-Weber syndrome

Somatic activating mutations in the GNAQ have been recently associated with several congenital genetic disorders and tumors; however, the molecular mechanism/etiology that leads to GNAQ somatic mosaic mutation are unknown. Here, we reported a case of Sturge-Weber Syndrome (SWS) manifesting cutaneous vascular malformations (hemifacial Port-wine stain), cerebral and ocular vascular abnormalities (including epilepsy and glaucoma) and harboring a c.548G>A (p.R183Q) somatic mosaic mutation in GNAQ. Computational modeling studies were performed to assistant with the comprehension of the functional impact of p.R183Q and p.Q209L mutations in GNAQ, which encodes a G protein subunit alpha q (Gαq). The p.R183Q mutation was predicted to abolish hydrogen bonds between R183 residue and GDP molecule, destabilizing the inactive GDP-bound conformation of the Gαq mutants. Furthermore, replacement of R183 by Q183 residue was predicted to promote conformation changes in protein surface features affecting the switch I region, a key region that undergoes conformational changes triggered by receptor binding during signal transduction. In addition, replacement of Q209 by L209 residue was predicted to affect the molecular interaction between Gαq and Gβ subunit, impairing formation of the inactive heterotrimeric complex. These findings, in association with PPI network analysis, indicate that p.R183Q and p.Q209L mutations result in the over-activation of different downstream effectors, which in turn will determine the distinct cell responses and phenotype. These findings bring new insights on molecular etiology of vascular malformations associated to SWS and on different mechanisms underlying hyperactivation of downstream pathways to Gαq.

Leveraging a Sturge-Weber Gene Discovery: An Agenda for Future Research

Sturge-Weber syndrome (SWS) is a vascular neurocutaneous disorder that results from a somatic mosaic mutation in GNAQ, which is also responsible for isolated port-wine birthmarks. Infants with SWS are born with a cutaneous capillary malformation (port-wine birthmark) of the forehead or upper eyelid which can signal an increased risk of brain and/or eye involvement prior to the onset of specific symptoms. This symptom-free interval represents a time when a targeted intervention could help to minimize the neurological and ophthalmologic manifestations of the disorder. This paper summarizes a 2015 SWS workshop in Bethesda, Maryland that was sponsored by the National Institutes of Health. Meeting attendees included a diverse group of clinical and translational researchers with a goal of establishing research priorities for the next few years. The initial portion of the meeting included a thorough review of the recent genetic discovery and what is known of the pathogenesis of SWS. Breakout sessions related to neurology, dermatology, and ophthalmology aimed to establish SWS research priorities in each field. Key priorities for future development include the need for clinical consensus guidelines, further work to develop a clinical trial network, improvement of tissue banking for research purposes, and the need for multiple animal and cell culture models of SWS.

Sturge-Weber syndrome and port-wine stains caused by somatic mutation in GNAQ

BACKGROUND

The Sturge-Weber syndrome is a sporadic congenital neurocutaneous disorder characterized by a port-wine stain affecting the skin in the distribution of the ophthalmic branch of the trigeminal nerve, abnormal capillary venous vessels in the leptomeninges of the brain and choroid, glaucoma, seizures, stroke, and intellectual disability. It has been hypothesized that somatic mosaic mutations disrupting vascular development cause both the Sturge-Weber syndrome and port-wine stains, and the severity and extent of presentation are determined by the developmental time point at which the mutations occurred. To date, no such mutation has been identified.

METHODS

We performed whole-genome sequencing of DNA from paired samples of visibly affected and normal tissue from 3 persons with the Sturge-Weber syndrome. We tested for the presence of a somatic mosaic mutation in 97 samples from 50 persons with the Sturge-Weber syndrome, a port-wine stain, or neither (controls), using amplicon sequencing and SNaPshot assays, and investigated the effects of the mutation on downstream signaling, using phosphorylation-specific antibodies for relevant effectors and a luciferase reporter assay.

RESULTS

We identified a nonsynonymous single-nucleotide variant (c.548G→A, p.Arg183Gln) in GNAQ in samples of affected tissue from 88% of the participants (23 of 26) with the Sturge-Weber syndrome and from 92% of the participants (12 of 13) with apparently nonsyndromic port-wine stains, but not in any of the samples of affected tissue from 4 participants with an unrelated cerebrovascular malformation or in any of the samples from the 6 controls. The prevalence of the mutant allele in affected tissues ranged from 1.0 to 18.1%. Extracellular signal-regulated kinase activity was modestly increased during transgenic expression of mutant Gαq.

CONCLUSIONS

The Sturge-Weber syndrome and port-wine stains are caused by a somatic activating mutation in GNAQ. This finding confirms a long-standing hypothesis. (Funded by the National Institutes of Health and Hunter's Dream for a Cure Foundation.).

Advances in Sturge-Weber syndrome

PURPOSE OF REVIEW

Recent neuroimaging, clinical and molecular neuropathologic studies have provided new insights into the neurologic aspects of Sturge-Weber syndrome and are summarized here.

RECENT FINDINGS

Molecular studies suggest that abnormal brain blood vessel vasoactive and extracellular matrix molecule expression, as well as aberrant brain vascular innervation, contribute to the vascular malformation and its consequences. New magnetic resonance sequences may be useful for the early diagnosis of Sturge-Weber syndrome and perfusion magnetic resonance imaging, single photon emission computed tomography imaging, and positron emission tomography imaging studies are suggesting that decreased brain blood flow combined with altered hemodynamics during prolonged seizures may contribute to the neurologic declines in Sturge-Weber syndrome.

SUMMARY

Recent advances in our understanding of the neurologic issues offer promise for preventing brain injury in Sturge-Weber syndrome. More research is needed to translate advances in molecular research and neuroimaging advances into new treatment strategies for the disease.

Genetic aspects of neurocutaneous disorders

Among the conditions that are included under the heading of "neurocutaneous disorders" are neurofibromatosis 1, tuberous sclerosis complex, von Hippel-Lindau, incontinentia pigmenti, Sturge-Weber syndrome, hypomelanosis of Ito, and linear nevus sebaceous syndromes. The clinical features, pathogenesis, and neurobiological basis of some of these disorders are discussed in other articles in this issue. We will focus on genetic aspects of a selected subgroup of these conditions, concentrating on the genetic defect, mutation spectrum, clinical genetic testing, and issues pertinent to counseling.

Sturge-Weber Syndrome Associated With Other Abnormalities

OBJECTIVE

To develop hypotheses regarding the relationship between Sturge-Weber syndrome (SWS) and other abnormalities in a subset of patients.

DESIGN

We retrospectively reviewed medical records in a group of 28 patients with SWS, noting the main features of SWS and accompanying unexpected abnormalities. We also conducted a literature review of abnormalities associated with SWS.

RESULTS

Twenty-eight medical records of patients with SWS were reviewed. Of this number, we found 8 (29%, 2 female) patients who manifested other abnormalities. Our review of the literature uncovered 15 additional cases with associated abnormalities.

CONCLUSIONS

We hypothesize that the abnormalities associated with SWS suggest testable insights regarding pathogenesis and that chromosome 17p1-p13 may be a candidate region for genes involved with SWS. We also propose that some patients with SWS may have disorders of cholesterol biosynthesis or carbohydrate glycosylation.

[Intracranial arteriovenous malformations: review of epidemiologic and genetic data]

Estimation of prevalence and incidence rates in a disease is crucial to estimate the risk of the natural evolution of the disease. We have reviewed published data on intracranial AVM and have noted that reported estimated risks were quite variable mainly due to the lack of population-based prospective data. Nonetheless, estimation of these parameters can be made from selected populations. We will note also that there is no published data confirming a genetic origin for the most frequent group of sporadic AVM.

Sturge-Weber syndrome

Sturge-Weber syndrome is a sporadic neurocutaneous disease characterized by facial port-wine stain, ocular abnormalities (glaucoma and choroidal hemangioma) and leptomeningeal angioma. Although the precise pathogenesis is unknown, available data regarding genetics, embryogenesis, and pathologic features are briefly reviewed. Clinical features vary from mild incomplete forms to full-blown disease with facial stain, seizures, and glaucoma. Frequencies of associated complications are reviewed. To plan treatment and further follow-up, diagnosis of glaucoma and intracranial involvement, even if asymptomatic, is fundamental in children at risk. Early neuroimaging features are important to recognize. Management of patients with Sturge-Weber syndrome is focused on treating associated neurologic and ocular abnormalities.

Pathophysiology of Sturge-Weber syndrome

Sturge-Weber syndrome is a neurocutaneous disorder classically presenting with a facial port-wine stain, vascular eye abnormalities, and an ipsilateral occipital leptomeningeal angioma. Children with Sturge-Weber syndrome often develop progressive neurologic problems. Data on the pathophysiology of Sturge-Weber syndrome are briefly reviewed. The embryologic, genetic, and pathologic considerations are discussed, as are theories regarding the mechanisms of the degenerative brain changes. Sturge-Weber syndrome likely results from an early embryologic malformation of vascular development affecting the development of the nearby skin, eye, and brain structures. Studies suggest that complex molecular interactions contribute to the abnormal development and function of blood vessels in Sturge-Weber syndrome. Neurologic deterioration in Sturge-Weber syndrome is likely secondary to impaired blood flow to the brain and is worsened by the presence of seizures. Insights from related areas are discussed, and future research studies are suggested.

Phakomatosis pigmentovascularis II A and II B: clinical findings in 24 patients

Nearly 200 cases of phakomatosis pigmentovascularis (PPV) have been reported worldwide, most of them of Japanese origin. There are 5 types and 10 subtypes of PPV. Its etiology might be explained by the twin spotting phenomenon. The relative frequency of PPV at the National Institute of Pediatrics was 5.8 per 100,000 pediatric patients and 0.634 per 100,000 dermatological patients. We report 24 cases of PPV with an average follow up of 5 years and the following findings: PPV type II A in 4 male and 2 female patients with melanosis bulbi in 3 and glaucoma in 1. PPV type II B in 7 male and 11 female patients, with melanosis bulbi in 9, glaucoma in 9, iris mammillations in 2, Sturge Weber syndrome in 6 female patients, and Klippel-Trenaunay syndrome in 2 males, hemifacial, hemicorporal, or limb hypertrophy without venous insufficiency in 6 female and 4 male patients. During the follow-up time of 60 months, progressive fading of melanotic and vascular macules were observed in 7 patients. No other types of PPV were found. Systemic involvement in PPV was related to the body surface area affected by the vascular macules. Ectodermal and mesodermal migration disorders might be involved in the pathogenesis of PPV.

Increased fibronectin expression in sturge-weber syndrome fibroblasts and brain tissue

Sturge-Weber syndrome (SWS) is a neurocutaneous disorder that presents with a facial port-wine stain and a leptomeningeal angioma. Fibronectin expression regulates angiogenesis and vasculogenesis and participates in brain tissue responses to ischemia and seizures. We therefore hypothesized that abnormal gene expression of fibronectin and other extracellular matrix genes would be found in SWS brain tissue and SWS port-wine skin fibroblasts. Fibronectin gene and protein expression from port-wine-derived fibroblasts were compared with that from normal skin-derived fibroblasts of four individuals with SWS using microarrays, reverse transcriptase-PCR, Western analysis, and immunocytochemistry. Fibronectin gene and/or protein expression from eight SWS surgical brain samples was compared with that in two surgical epilepsy brain samples and six postmortem brain samples using microarrays, reverse transcriptase-PCR, and Western analysis. The gene expression of fibronectin was significantly increased (p < 0.05) in the SWS port-wine-derived fibroblasts compared with that of fibroblasts from SWS normal skin. A trend for increased protein levels of fibronectin in port-wine fibroblasts was found by Western analysis. No difference in the pattern of fibronectin staining was detected. The gene expression of fibronectin was significantly increased (p < 0.05), and a trend for increased fibronectin protein expression was found in the SWS surgical brain samples compared with the postmortem controls. These results suggest a potential role for fibronectin in the pathogenesis of SWS and in the brain's response to chronic ischemic injury in SWS. The reproducible differences in fibronectin gene expression between the SWS port-wine-derived fibroblasts and the SWS normal skin-derived fibroblasts are consistent with the presence of a hypothesized somatic mutation underlying SWS.

Klippel-Trenaunay syndrome and Sturge-Weber syndrome: variations on a theme?

We describe a patient with a complex neurocutaneous syndrome of congenital vascular malformations, abnormalities of brain and bones, and soft tissue hypertrophy of one leg. According to eponymous classification schemes, the patient can be assigned to two different clinical entities. Using the lethal gene theory it is possible to unify these different syndromes and to explain the overlap and diversity of these congenital vascular syndromes. We argue that it is better to describe such vascular malformation syndromes in anatomical/histological or functional terms and map the extent of the disease, rather than name it according to the eponymous classification.

Encephalofacial angiomatosis sparing the occipital lobe and without facial nevus: on the spectrum of Sturge-Weber syndrome variants?

We report two cases of leptomeningeal angiomatosis in atypical frontoparietotemporal locations without an associated facial port-wine stain. Evidence of a leptomeningeal angioma was found in each when they were evaluated for headaches and seizures. The diagnosis of a leptomeningeal angioma was suggested by calcifications noted on computed tomographic scan of the head and confirmed with contrast-enhanced magnetic resonance images of the brain. We hypothesize that given the lack of occipital involvement with the angioma, and therefore the noncontiguous nature of this lesion with the developing upper facial ectoderm, the failure to develop a facial angioma would be expected. We found that the useof an anticonvulsant along with a migraine prophylactic medication appeared to have the greatest efficacy in these two cases, whereas anticonvulsants alone were less helpful. This diagnosis should be considered in any child presenting with seizures or complicated migraines and intracranial calcifications.

Predominance of brain tumors in an extended Li-Fraumeni (SBLA) kindred, including a case of Sturge-Weber syndrome

BACKGROUND

Li-Fraumeni syndrome (LFS) is characterized by a plethora of cancers, most prominent of which is carcinoma of the breast followed by sarcomas, brain tumors, leukemia, lymphoma, lung carcinoma, and adrenocortical carcinoma (therefore, also referred to by the acronym SBLA syndrome).

METHODS

The family reported herein was first described 2 decades ago. Now extensive follow-up has shown the predictable occurrence of these tumor types, in addition to an excess of brain tumors and the finding of Sturge-Weber syndrome (SWS) in an LFS-affected family member.

RESULTS

A possible new feature of the disorder, suggestive of SWS, was identified in a patient in the direct genetic lineage. This patient had a rhabdomyosarcoma of the eyelid at age 29 months and at age 14 years was diagnosed with lymphoblastic lymphoma/acute lymphoblastic leukemia. A remarkable excess of brain tumors was identified in this family through this current update. The p53 germ-line mutation was not identified in any affected member of this family.

CONCLUSIONS

To the authors' knowledge, this is the first example of SWS in the context of LFS. Brain tumors appear to be an important component of the tumor spectrum of LFS, as evidenced in this family.

[The results of recent research in neurocutaneous syndromes]

Identification of NF1, TSC2 and TSC1 genes has enabled us to focus on their function and regulation. Evidence suggests that these genes are tumor suppressor genes. Malignant tissues in NF1 and hamartomatous tissues in TSC show "loss of heterozygosity" in NF1 and TSC1, 2 genes, respectively. In addition, in the Eker rat with hereditary renal carcinoma, a mutation in the TSC2 gene has been identified. In this review I mentioned briefly several issues to be clarified in the near future.

Perspectives on craniofacial asymmetry. VI. The hamartoses

The hamartoses are a large group of disorders with autosomal dominant inheritance or sporadic occurrence. The genes responsible for some have been localized to specific chromosomes and in several instances, genetic heterogeneity has been established. Thus neurofibromatosis and tuberous sclerosis are no longer single entities. For example, the gene for Type I neurofibromatosis is on chromosome 17 and the gene for Type II is on chromosome 22. In this paper, genetic aspects of the hamartoses are updated and asymmetry is discussed in Sturge-Weber angiomatosis, epidermal nevus syndrome, Gardner syndrome, neurofibromatosis, and Proteus syndrome.

The phakomatoses: Part II. von Hippel-Lindau disease, Sturge-Weber syndrome, and less common conditions

The phakomatoses appear to represent a group of disorders characterized, in part, by the common features of neuroectodermal mal-development, undecided differentiation of cells, and disturbed patterns of cell migration. With progress in genetics and cell biology, the precise deficits in the genome and the specific biochemical abnormalities associated with these defects will be elucidated. It is expected that the apparent diversity of these lesions will then be understood as a coherent series of missteps along the common pathway of normal growth and development.

The Sturge-Weber syndrome: correlation between the clinical status and radiological CT and MRI findings

In the Sturge-Weber syndrome facial venous and leptomeningeal angiomas are associated. We studied 14 consecutive cases with clinical and radiological evaluations [computed tomography (CT) and magnetic resonance imaging (MRI)]. Radiological studies demonstrated the extent and patency of the leptomeningeal angiomatous malformation, the degree of parenchymal atrophy, the presumed ischemic changes affecting the gray and white matter, the presence and extent of cortical calcifications, the prominence of the choroid plexus, the parenchymal venous anomalies, and the diploic prominence in the affected side. The white matter alterations, being greater, the extent of lobar involvement, and the degree of parenchymal atrophy all correlated with the patient's clinical status being poorer. MRI is more efficient in the detection of the radiological findings related to the clinical status: seizure control, degree of psychomotor development and hemiparesis. Therefore, MRI is the imaging modality of choice in the diagnosis of these patients.

Vascular disorders

Cutaneous vascular abnormalities are a feature of many syndromes with multisystemic involvement. The most common associations are hypertrophy of underlying soft tissue and bone, as in the Klippel-Trenaunay-Weber and Sturge-Weber syndromes, visceral vascular lesions with hemorrhage, as in hereditary hemorrhagic telangiectasia and blue rubber bleb nevus syndrome, and neurologic alterations, as in Fabry's disease, ataxia-telangiectasia, and the Sturge-Weber syndrome.

[Association on Sturge Weber and Klippel Trenaunay Weber syndromes. Apropos of 2 cases]

The present paper describes two patients with Sturge-Weber and Klippel Trénaunay-Weber syndromes. Some etiopathogenic factors are analyzed. We suggest that the association of both diseases in the same patient may be due to a single autosomal dominant gene.

Chromosome abnormalities in neurological diseases

The current status of research into chromosomal abnormalities in neurological diseases is reviewed. The only possible association between chromosome aberration and neurological disorder is found in ataxia telangiectasia and in tumours of the nervous system. In the remaining diseases reviewed, no specific association was confirmed. This was expected to some extent, since the majority of these diseases (spinal muscular atrophies, muscular dystrophies, etc.) are due to single gene defects.

[Phakomatoses. Ophthalmological and genetic aspects]

Detailed ophthalmological and genetic studies on the four classical types of phacomatoses and more succint studies of twelve syndromes which can be considered as atypical forms of phacomatoses. Discussion of the association between the different forms of phacomatoses. Establishment of genetic prognoses.

Familial translocation t(3p-;21q+) associated with both Down's and Sturge-Weber's syndrome in unbalanced state

A boy with both Down's and Sturge-Weber's syndrome was found to have a partial trisomy 21 as a consequence of a familial translocation t(3p-;21q+) which is not reciprocal. Judging from the structure of the involved chromosomes studied by banding and photometrical techniques, the loss of relatively large material of 21q is to be suggested. The meiotic segregation appears to depend on the involved 3p segment and not on the involved centromere of No. 21 as actually expected. The pedigree of the family shows 6 balanced carriers through 3 generations in addition to the propositus. The risk of having offspring with Down's syndrome obviously concerns female carriers in the first place, whereas the male carriers rather produce balanced carriers. Of the additional Sturge-Weber's syndrome there was no cytogenetical cause as expected.

[Difficulties in genetic counseling in phakomatosis]

It is often difficult to establish a valid pedigree in a family, a member of which shows one or another phakomatosis. It is indispensable to examine all the members of the family in order to detect the "formes frustes" or the atypical and abortive forms, which are frequent, and in order to establish a genetic prognosis and to give a genetic counseling, taking the penetrance into account.