Stéphanie Guey

Objective: To report an atypical phenotype associated with two rare COL4A1 glycine missense variants located in exon 23. Methods: Clinical, neuropsychological, and brain imaging data of four patients with such variants were reported. Results: Four unrelated patients presented with late‐onset cognitive alterations starting between 55 and 65 years of age. Brain magnetic resonance imaging (MRI) showed extensive white‐matter hyperintensities on T2 or Flair images in all subjects, associated with multiple dilated perivascular spaces in the basal ganglia with features of status cribrosum in the three oldest individuals. None of the patients had a history of haemorrhagic stroke. Three of these patients had previously experienced mood disturbances. All had a family history of depression and/or suicide. Three of these unrelated patients shared a rare missense variant p.(Gly474Arg) in COL4A1 , whereas the fourth one carried a p.(Gly486Glu) variant; these two variants affect two closely linked glycine residues encoded by exon 23 and located in a major cell‐binding site of the triple helix. Conclusion: Missense variants affecting closely clustered glycine residues within the glycine–X–Y repeats encoded by exon 23 of COL4A1 are associated with an atypical, late‐onset form of cerebral small vessel disease, characterised by diffuse leukoencephalopathy with a status cribrosum pattern and predominantly cognitive and/or neuropsychiatric manifestations.

Background and Purpose: Familial cerebral cavernous malformations (fCCM) may cause focal neurological deficits (FND) due to hemorrhagic or non‐hemorrhagic events and epileptic seizures (ES). With the widespread use of magnetic resonance imaging (MRI) and genetic testing, diagnosis is now frequently established at a presymptomatic stage, before any clinical manifestation. However, the subsequent risk of a first clinical event in these individuals remains poorly defined. Methods: We conducted a cohort‐based analysis of retrospectively collected longitudinal data from 79 patients with fCCM who were asymptomatic at diagnosis (median age, 41.7 years) and managed in a national referral center. Results: Over 649.6 patient‐years (median follow‐up, 4.0 years), 23 patients (29%) experienced a first clinical event. Post‐diagnostic event‐free survival was approximately 97% at 1 year, 79% at 5 years, and 69% at 10 years. Incidence rates for a first event were 35.4 per 1000 person‐years for any first event (FND or ES), 23.1 per 1000 person‐years for a first FND, and 15.4 per 1000 person‐years for a first ES. Male sex was independently associated with higher risk (HR 4.20; 95% CI, 1.60–11.04; p = 0.0036). Conclusions: These data provide pragmatic post‐diagnostic risk estimates to guide counseling and surveillance in asymptomatic fCCM.

L’angiopathie moyamoya (MMA) est une affection cérébro-vasculaire rare dont la physiopathologie est mal connue. Elle est caractérisée par l’association d’une sténose des terminaisons des carotides internes et d’un réseau de néovaisseaux à la base du crâne. Il en existe une forme pure (MoyaMoya Disease ou MMD) et une forme syndromique (MoyaMoya Syndrome ou MMS). Dix pourcents des cas de MMA sont familiaux. En Asie, une très forte association a été démontrée entre MMD et un variant de susceptibilité unique dans le gène RNF213, variant totalement absent chez les Caucasiens. Par ailleurs, une douzaine de gènes impliqués dans des formes mendéliennes de MMS ont été identifiés à ce jour mais ne concernent qu’un très faible nombre de patients. La pénétrance de la MMA dans ces formes est le plus souvent très faible et aucun modèle animal n’a de ce fait pu être établi. L’identification d’autres gènes impliqués dans la MMA pourrait permettre, au-delà des applications cliniques immédiates, de mieux caractériser les pathways impliqués et d’aider ainsi à la compréhension des mécanismes physiopathologiques. L’objectif de cette thèse était de poursuivre le démantèlement moléculaire de cette affection par l’analyse moléculaire d’une cohorte multiethnique de 126 index MMA (80% MMD/ 20% MMS) et 66 de leurs apparentés pour lesquels nous disposions de données phénotypiques détaillées et d’un séquençage exome entier (WES, Whole Exome Sequencing). Treize de ces index appartenaient à des familles multiplex et 113 étaient des formes sporadiques (dont 15 trios et 6 index issus d’unions consanguines). Nous avons tout d’abord réalisé une analyse d’association de type « burden-test » visant à comparer la charge en variants rares de RNF213 entre 73 index MMA caucasiens et une cohorte de573 contrôles de même origine ethnique. Nous avons démontré l’existence d’une association significative entre variants rares non-synonymes de RNF213 et MMA chez les Caucasiens, association encore plus marquée lorsque l’analyse était restreinte aux cas familiaux et/ou de début précoce. Les variants identifiés chez les patients se regroupaient dans un hotspot C-terminal englobant le domaine RING-finger.D’autre part, nous avons conduit une « analyse individuelle ou familiale » des données de WES des familles multiplex, trios, index consanguins et index sporadiques de début précoce. Les gènes candidats identifiés ont ensuite été criblés dans l’ensemble de la cohorte de 126 index à la recherche d’une récurrence génétique. L’analyse des trios a mis en évidence l’implication de variants rares de novo du gène CBL (un gène majeur de la voie RAS-MAPK connu à la fois pour son implication dans un syndrome Noonan-like et dans une forme particulière de leucémie de l’enfant) dans des formes mendéliennes de MMA de début pédiatrique ne présentant ni phénotype Noonan-like, ni leucémie. L’analyse des index consanguins a permis d’identifier une nouvelle forme mendélienne de MMA liée à des mutations récessives perte de fonction dans le gène NOS3 codant pour la Nitric oxide(NO) synthase endothéliale, pointant le rôle de la voie du NO dans la physiopathologie de la MMA.Ce travail souligne l’architecture complexe de la MMA, avec l’intervention d’une part de variants de susceptibilité et d’autre part de variants mendéliens impliqués dans une très petite proportion de patients. L’analyse en cours des données cette cohorte par une approche de tests de charge exome-wide, devrait permettre d’identifier de nouveaux gènes de susceptibilité. Enfin l’analyse de modèles murins KO pour NOS3 pourrait aider à l’obtention d’un premier modèle murin de MMA.

BACKGROUND: Cerebral small vessel disease (CSVD) is a major cause of stroke and vascular cognitive impairment, yet its mechanisms remain incompletely understood. While heterozygous point mutations in COL4A1 and COL4A2 are established monogenic cause of CSVD, the contribution of copy number gains involving these 2 genes has only recently been recognized. We aimed to define the clinical and radiological spectrum of COL4A1/2 duplications and triplications in adults. METHODS: We report 7 adult probands carrying duplications or triplications of COL4A1 and COL4A2 , in whom no pathogenic variants were identified in other known CSVD genes. Targeted high-throughput sequencing, quantitative multiplex polymerase chain reaction of short fluorescent fragments, and SNP arrays were used to confirm and characterize genomic rearrangements spanning the 13q33q34 region. RESULTS: Genomic rearrangements ranged from 328 kb to 11.8 Mb, involving complete or partial duplication/triplication of COL4A1/2 . Patients presented heterogeneous cerebrovascular manifestations, including ischemic and hemorrhagic events, motor impairment, and cognitive decline. Brain magnetic resonance imaging consistently showed extensive white matter hyperintensities, lacunes (particularly in the pons), microbleeds, and, in some cases, saccular aneurysms or arterial dolichoectasia. Only 2 probands had a positive family history of CSVD. CONCLUSIONS: This large series confirms the pathogenicity of COL4A1/2 duplications and triplications in adult-onset CSVD. Phenotypic variability likely reflects differences in duplication/triplication size, gene content, and modifying factors. Our findings highlight a distinct cerebral-only phenotype linked to gene dosage–related overexpression and underscore the importance of screening for copy number variations in patients with otherwise unexplained cerebral microangiopathy, even in the absence of a family history.

BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary cerebral small-vessel disease. The CADASIL MRI Inventory Tool summarizes individual MRI findings as simple, type-specific lesion levels. We assessed the predictive value of these levels beyond clinical information. METHODS: At baseline, CADASIL MRI Inventory Tool levels were assigned for periventricular, deep, and superficial white matter hyperintensities, lacunes, cerebral microbleeds, perivascular spaces in the centrum semiovale and basal ganglia, superficial and deep atrophy, large infarcts, and macrobleeds. Outcomes included stroke, migraine with aura (MA), moderate or severe cognitive impairment, and disability, which were assessed at baseline and during 2-year follow-up. Multivariable logistic regression was performed, with adjustment for age, sex, vascular risk factors, mutation location, and education level. RESULTS: We analyzed 743 patients from France, Germany, and Taiwan (mean age, 53±12; 55% with prior stroke; 35% with MA; 15% with disability; 18% with cognitive impairment). At baseline, higher deep white matter hyperintensities and lacune levels were associated with stroke, whereas cerebral microbleeds and superficial atrophy were inversely associated with MA. Superficial atrophy and periventricular white matter hyperintensities were higher, and superficial white matter hyperintensities were lower, among those with cognitive impairment, whereas deep atrophy and lacunes were linked to disability. Over 2 years (n=547), 11.7% experienced ischemic stroke events, 22.2% MA attacks, 6.5% developed disability, and 6.9% moderate or severe cognitive impairment. After adjustment, lacune levels independently predicted ischemic stroke events (odds ratio, 6.10 [95% CI, 2.09–26.02] for all levels combined). Superficial atrophy and higher superficial white matter hyperintensities predicted a lower risk of MA (odds ratio, 0.29 and 0.21 [95% CI, 0.12–0.68] and [0.06–0.77]). Lacunes and deep atrophy predicted disability, and lacunes with superficial atrophy predicted cognitive impairment. CONCLUSIONS: CADASIL MRI Inventory Tool lesion levels are differentially associated with CADASIL manifestations and provide independent 2-year prognostic information beyond clinical covariates. These simple measures may supplement clinical evaluation to improve short-term risk stratification and support patient selection in clinical trials.

Familial cavernous malformations (FCMs) are vascular lesions that pose a lifelong risk of symptomatic hemorrhage (SH) and seizures, yet their natural history remains unclear. This study aims to determine the cumulative lifetime risk of a first SH and/or seizure and assess whether genetic variations influence these risks. This international, multicenter retrospective cohort study included data from 16 tertiary referral centers and 1 patient advocacy group. Eligible patients had confirmed or suspected FCM, available magnetic resonance imaging (MRI) data, documented baseline clinical features, and longitudinal follow-up (FU). Functional outcomes were assessed using the modified Rankin Scale (mRS) at last FU. Direct adjusted survival curves and mixed-effects Cox regression analyses were performed to estimate cumulative lifetime risk. The association between genetic variations and SH/seizure rates was evaluated, and mixed-effects logistic regression assessed the effect of SH/seizures on mRS outcomes. A total of 1,592 patients with FCM were included, with a mean age of 37.6 years (SD 17.1) and 55.7% female. The median FU was 42 years (IQR: 27-55), totaling 64,146 person-years. Of these, 869 (54.6%) had confirmed FCM, 775 (48.7%) experienced at least 1 hemorrhage, and 447 (28.1%) had at least 1 seizure. Genetic testing was performed in 47.7%, identifying CCM1 (31.0%), CCM2 (4.8%), and CCM3 (1.9%) variations. The lifetime risk of a first SH was ∼80%, with an event rate that remained constant beyond age 20. The lifetime risk of a first seizure was ∼45%. Patients with CCM3 variations exhibited a more aggressive hemorrhagic course than those with CCM1 (hazard ratio 1.799, 95% CI 1.008-3.208). SH and seizures were independently associated with worse mRS outcomes at last FU. The event rate of SH and seizures remained stable over time, leading to high cumulative lifetime risks. Patients with CCM3 variations exhibited a more aggressive disease course. Limitations include the non-population-based design, selection bias from tertiary centers, retrospective data collection, and variability in data extraction across centers. However, this study represents the largest international FCM cohort to date, improving the precision of risk estimates and providing valuable insights into disease progression.

BACKGROUND: Intracerebral hemorrhage (ICH) is increasingly recognized in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, especially in Asian patients with the NOTCH3 R544C variant. The associations between ICH, NOTCH3 variants, and hypertension remain unclear. METHODS: We enrolled patients from 2 independent cohorts with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy in France (recruited since 2003) and Taiwan (recruited since 2019) and performed a cross-sectional retrospective analysis. Clinical history and evaluation were collected using standardized questionnaires and scales, while neuroimaging features were assessed with the CADA-MRIT inventory tool. Patients with and without a history of ICH were compared. Logistic regression and mediation analyses were conducted to identify factors associated with ICH. RESULTS: Of 552 patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (440 from France and 112 from Taiwan), 34 (6.2%) had a history of ICH. Patients with ICH were older (62.9±11.4 versus 53.4±12.3 years), had a higher proportion of the NOTCH3 R544C variant (79.4% versus 15.3%), and had hypertension (85.3% versus 24.9%). Analysis of magnetic resonance imaging data showed that they had more cerebral microbleeds, worse cerebral atrophy, and higher number of dilated perivascular spaces in basal ganglia. Hypertension (odds ratio, 7.90 [95% CI, 2.83–22.08]) and NOTCH3 R544C variant (odds ratio, 9.91 [95% CI, 3.84–25.57]) were each independently associated with ICH, while no multiplicative interaction was detected between these 2 factors ( P _interaction =0.81). Having both NOTCH3 R544C variant and hypertension carried an additive effect on the risk of ICH (36.9% if both present, 8.8% if having NOTCH3 R544C variant without hypertension, 5.4% if having hypertension without NOTCH3 R544C variant, and 0.6% if both absent; P _trend NOTCH3 R544C variant on the occurrence of ICH would be explained by the effects of hypertension. CONCLUSIONS: Both the NOTCH3 R544C variant and hypertension appear to be independent risk factors for ICH in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, with a potential additive effect. However, due to the study’s cross-sectional design and population-specific factors, causality cannot be established. Prospective studies are thus needed to validate these findings and clarify underlying mechanisms.

Background: The COL4A1 and COL4A2 genes encode the alpha-1 and alpha-2 chains of type IV collagen, which are fundamental components of the basement membrane, playing key roles in both structural support and cellular regulation

Introduction: Type IV collagen, predominantly composed of the COL4A1 and COL4A2 genes, is a crucial component of the basement membrane, essential for maintaining vascular integrity

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most frequent small artery brain disease caused by pathogenic variants of the NOTCH3 gene. During the disease, we still do not know how the various deficits progress and develop with each other at different stages of the disease. We aim to model disease progression and identify possible progressive subgroups and the effects of different covariates on clinical worsening. Data were obtained from patients followed in the French CADASIL referral center, who were aged 25-80 years and had completed at least 2 visits and one of 14 clinical scores. Progression and variability were assessed using a disease course model (Leaspy). A Gaussian mixture model was used to identify different progression subgroups. Logistic regressions were used to compare the characteristics between groups. In 395 patients along 2,007 visits, the follow-up ranged from 6 months to 19 years, with a mean of 7.5 years. They were 45% men with a mean age of 52.2 years. The evolution curves of the different scores showed that clinical manifestations develop heterogeneously and can vary considerably depending on the disease stage. We identified an early-onset, rapidly progressing subgroup of patients with earlier motor symptoms and focal neurologic deficits (median time shift 59 [Q1-Q3 48.9-66.3], median acceleration rate 0.84 [0.07-1.31]) and a late-onset slowly progressing group with earlier cognitive symptoms (median time shift 69.2 [63.4-75.1], median acceleration rate -0.18 [-0.48 to 0.14]). Male sex, lower education level, hypertension, and NOTCH3 pathogenic variant location within epidermal growth factor-like repeat (EGFr) 1-6 were found to be associated with this group difference. Our results suggest a gradual and heterogeneous decline in different clinical and cognitive performances over the lifetime of patients with CADASIL. Two progression profiles-one rapid and early and the other, more delayed and slower-are possible after the onset of symptoms. A major limitation of our study is that the clusters were assessed post hoc, which may induce some bias. Overall, male sex, low level of education, pathogenic variant location in EGFr 1 to 6 domains, smoking, and/or arterial hypertension may affect the clinical progression of the disease.