Management of Inherited CNS Small Vessel Diseases: The CADASIL Example: A Scientific Statement From the American Heart Association

Multiorgan manifestations of COL4A1 and COL4A2 variants and proposal for a clinical management protocol

COL4A1/2 variants are associated with highly variable multiorgan manifestations. Depicting the whole clinical spectrum of COL4A1/2-related manifestations is challenging, and there is no consensus on management and preventative strategies. Based on a systematic review of current evidence on COL4A1/2-related disease, we developed a clinical questionnaire that we administered to 43 individuals from 23 distinct families carrying pathogenic variants. In this cohort, we extended ophthalmological and cardiological examinations to asymptomatic individuals and those with only limited or mild, often nonspecific, clinical signs commonly occurring in the general population (i.e., oligosymptomatic). The most frequent clinical findings emerging from both the literature review and the questionnaire included stroke (203/685, 29.6%), seizures or epilepsy (199/685, 29.0%), intellectual disability or developmental delay (168/685, 24.5%), porencephaly/schizencephaly (168/685, 24.5%), motor impairment (162/685, 23.6%), cataract (124/685, 18.1%), hematuria (63/685, 9.2%), and retinal arterial tortuosity (58/685, 8.5%). In oligosymptomatic and asymptomatic carriers, ophthalmological investigations detected retinal vascular tortuosity (5/13, 38.5%), dysgenesis of the anterior segment (4/13, 30.8%), and cataract (2/13, 15.4%), while cardiological investigations were unremarkable except for mild ascending aortic ectasia in 1/8 (12.5%). Our multimodal approach confirms highly variable penetrance and expressivity in COL4A1/2-related conditions, even at the intrafamilial level with neurological involvement being the most frequent and severe finding in both children and adults. We propose a protocol for prevention and management based on individualized risk estimation and periodic multiorgan evaluations.

Expanding the Neurological Phenotype of Anderson-Fabry Disease: Proof of Concept for an Extrapyramidal Neurodegenerative Pattern and Comparison with Monogenic Vascular Parkinsonism

Anderson-Fabry disease (AFD) is a genetic sphingolipidosis involving virtually the entire body. Among its manifestation, the involvement of the central and peripheral nervous system is frequent. In recent decades, it has become evident that, besides cerebrovascular damage, a pure neuronal phenotype of AFD exists in the central nervous system, which is supported by clinical, pathological, and neuroimaging data. This neurodegenerative phenotype is often clinically characterized by an extrapyramidal component similar to the one seen in prodromal Parkinson's disease (PD). We analyzed the biological, clinical pathological, and neuroimaging data supporting this phenotype recently proposed in the literature. Moreover, we compared the neurodegenerative PD phenotype of AFD with a classical monogenic vascular disease responsible for vascular parkinsonism and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). A substantial difference in the clinical and neuroimaging features of neurodegenerative and vascular parkinsonism phenotypes emerged, with AFD being potentially responsible for both forms of the extrapyramidal involvement, and CADASIL mainly associated with the vascular subtype. The available studies share some limitations regarding both patients' information and neurological and genetic investigations. Further studies are needed to clarify the potential association between AFD and extrapyramidal manifestations.

The protocol for an observational Australian cohort study of CADASIL: The AusCADASIL study

Introduction

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is a rare genetic condition with a broad phenotypic presentation. This study aims to establish the first Australian cohort of individuals affected by CADASIL (AusCADASIL) and examine its clinical features and longitudinal course, and to investigate neuroimaging and blood biomarkers to assist in early diagnosis and identify disease progression.

Methods

Participants will be recruited from six study centres across Australia for an observational study of CADASIL. We aim to recruit 150 participants with diagnosed CADASIL, family history of CADASIL or suspected CADASIL symptoms, and 150 cognitively normal NOTCH3 negative individuals as controls. Participants will complete: 1) online questionnaires on medical and family history, mental health, and wellbeing; 2) neuropsychological evaluation; 3) neurological examination and brain MRI; 4) ocular examination and 5) blood sample donation. Participants will have annual follow-up for 4 years to assess their progression and will be asked to invite a study partner to corroborate their self-reported cognitive and functional abilities.Primary outcomes include cognitive function and neuroimaging abnormalities. Secondary outcomes include investigation of genetics and blood and ocular biomarkers. Data from the cohort will contribute to an international consortium, and cohort participants will be invited to access future treatment/health intervention trials.

Discussion

AusCADASIL will be the first study of an Australian cohort of individuals with CADASIL. The study will identify common pathogenic variants in this cohort, and characterise the pattern of clinical presentation and longitudinal progression, including imaging features, blood and ocular biomarkers and cognitive profile.

Impact of arterial stiffness on cerebrovascular function: a review of evidence from humans and preclincal models

With advancing age, the cerebral vasculature becomes dysfunctional, and this dysfunction is associated with cognitive decline. However, the initiating cause of these age-related cerebrovascular impairments remains incompletely understood. A characteristic feature of the aging vasculature is the increase in stiffness of the large elastic arteries. This increase in arterial stiffness is associated with elevated pulse pressure and blood flow pulsatility in the cerebral vasculature. Evidence from both humans and rodents supports that increases in large elastic artery stiffness are associated with cerebrovascular impairments. These impacts on cerebrovascular function are wide-ranging and include reductions in global and regional cerebral blood flow, cerebral small vessel disease, endothelial cell dysfunction, and impaired perivascular clearance. Furthermore, recent findings suggest that the relationship between arterial stiffness and cerebrovascular function may be influenced by genetics, specifically APOE and NOTCH genotypes. Given the strength of the evidence that age-related increases in arterial stiffness have deleterious impacts on the brain, interventions that target arterial stiffness are needed. The purpose of this review is to summarize the evidence from human and rodent studies, supporting the role of increased arterial stiffness in age-related cerebrovascular impairments.

CADASIL: A NOTCH3-associated cerebral small vessel disease

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary cerebral small vessel disease (CSVD), pathologically characterized by a non-atherosclerotic and non-amyloid diffuse angiopathy primarily involving small to medium-sized penetrating arteries and leptomeningeal arteries. In 1996, mutation in the notch receptor 3 gene (NOTCH3) was identified as the cause of CADASIL. However, since that time other genetic CSVDs have been described, including the HtrA serine peptidase 1 gene-associated CSVD and the cathepsin A gene-associated CSVD, that clinically mimic the original phenotype. Though NOTCH3-associated CSVD is now a well-recognized hereditary disorder and the number of studies investigating this disease is increasing, the role of NOTCH3 in the pathogenesis of CADASIL remains elusive.

AIM OF REVIEW

This review aims to provide insights into the pathogenesis and the diagnosis of hereditary CSVDs, as well as personalized therapy, predictive approach, and targeted prevention. In this review, we summarize the current progress in CADASIL, including the clinical, neuroimaging, pathological, genetic, diagnostic, and therapeutic aspects, as well as differential diagnosis, in which the role of NOTCH3 mutations is highlighted.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, CADASIL is revisited as a NOTCH3-associated CSVD along with other hereditary CSVDs.