Neurological picture. Familial Sneddon's syndrome with microbleeds in MRI

A NOTCH3 homozygous nonsense mutation in familial Sneddon syndrome with pediatric stroke

Sneddon syndrome is a rare disorder affecting small and medium-sized blood vessels that is characterized by the association of livedo reticularis and stroke. We performed whole-exome sequencing (WES) in 2 affected siblings of a consanguineous family with childhood-onset stroke and identified a homozygous nonsense mutation within the epidermal growth factor repeat (EGFr) 19 of NOTCH3, p.(Arg735Ter). WES of 6 additional cases with adult-onset stroke revealed 2 patients carrying heterozygous loss-of-function variants in putative NOTCH3 downstream genes, ANGPTL4, and PALLD. Our findings suggest that impaired NOTCH3 signaling is one underlying disease mechanism and that bi-allelic loss-of-function mutation in NOTCH3 is a cause of familial Sneddon syndrome with pediatric stroke.

Sneddon Syndrome: A Comprehensive Overview

Sneddon syndrome (SS) is an episodic or chronic, slowly progressive disorder and characterized by generalized livedo racemosa (patchy, violaceous, skin discoloration) and recurrent cerebrovascular events. The histopathology of skin and brain is remarkable for a noninflammatory thrombotic vasculopathy involving medium- and small-sized dermal and cerebral arteries, respectively. Approximately 80% of the SS patients are women with a median age of diagnosis at 40 years. However, the onset of the disease during childhood have been reported. Etiopathogenesis of SS is unknown with 2 primary mechanisms proposed - autoimmune/inflammatory versus thrombophilia. SS is primarily classified as antiphospholipid positive or negative type. Neurological manifestations usually occur in 3 phases: (1) prodromal symptoms such as headaches, dizziness, and vertigo, (2) recurrent strokes, and (3) early onset dementia. Livedo racemosa precedes the onset of recurrent strokes by more than 10 years, but in many instances, the significance of the skin lesion is recognized only after the appearance of the stroke. The involvement of the heart valves, systolic labile hypertension, and retinal changes are also commonly associated with this syndrome. Treatment of SS is primarily based on anecdotal reports. Antiplatelet and antithrombotic agents are used for secondary stroke prophylaxis, and a recent study showed a relatively lower stroke recurrence rate with the universal use of antiplatelet/antithrombotic agents. Routine use of anti-inflammatory or immunosuppressive therapies is controversial. Neuropsychiatric prognosis of SS is relatively poor with predominant deficits in the concentration, attention, visual perception, and visuospatial skills.

Sneddon's syndrome: a comprehensive review of the literature

Sneddon's syndrome (SS) is a rare non-inflammatory thrombotic vasculopathy characterized by the combination of cerebrovascular disease with livedo racemosa(LR). The Orpha number for SS is ORPHA820. It has been estimated that the incidence of SS is 4 per 1 million per annum in general population and generally occurs in women between the ages of 20 and 42 years. LR may precede the onset of stroke by years and the trunk and/or buttocks are involved in nearly all patients. The cerebrovascular manifestations are mostly secondary to ischemia (transient ischemic attacks and cerebral infarct). Other neurological symptoms range from headache, cerebral hemorrhage, seizures, cognitive and psychiatric disturbances. The involved internal organs include heart, kidney, and eyes. Histological findings of skin are characteristic and the involved vessels are small to medium-sized arteries at the border of dermis to subcutis with a distinct histopathological time course. The main diagnostic criteria are general LR with typical histopathological findings on skin biopsy and focal neurological deficits. The pathogenesis is related to hypercoagulable state and intrinsic small-vessel vasculopathy. The optimal management remains an unsolved problem and long-term anticoagulation have been recommended for cerebral ischemic events based on the presumed pathogenesis. There are controversial results in treatment of SS with immunomodulatory agents. The aim of this review is to comprehensively discuss this disease.