Genetic neurocutaneous syndromes - Sturge–Weber syndrome

Description

Sturge-Weber syndrome - a sporadic (non-inherited) neurocutaneous disorder from a somatic mosaic mutation in GNAQ, causing a facial port-wine stain, leptomeningeal vascular malformation, and glaucoma in the classic triad

Sporadic, not inherited (a post-zygotic somatic mutation, present only in the affected tissue, not in the germline) - explains why it does not run in families and why recurrence risk to offspring is not elevated

A somatic activating GNAQ mutation occurring early in embryonic development produces a patchy (mosaic) distribution of abnormal, dilated capillary-venous vessels - affecting skin (port-wine stain, typically in the trigeminal V1 distribution), the leptomeninges (leading to seizures, hemiparesis, and progressive neurological decline), and the eye (glaucoma from abnormal ocular vasculature/venous drainage)

Facial port-wine stain in the trigeminal V1 (ophthalmic) distribution carries a substantially higher risk of associated leptomeningeal involvement than a port-wine stain in other facial distributions - a key clinical risk stratifier for further neuroimaging
MRI brain with contrast - identifies leptomeningeal angiomatosis, often with characteristic "tram-track" calcification (better seen on CT) in affected areas, and can show progressive cerebral atrophy in the affected hemisphere over time
Regular ophthalmological screening for glaucoma, which can develop at any age and may not be symptomatic until advanced

Low-dose aspirin is used by some centres to reduce stroke-like episode/seizure frequency, based on theoretical benefit from reducing microthrombosis in the abnormal vasculature, though evidence is not definitive
Anticonvulsants for seizure control (often the dominant management issue); refractory seizures may require epilepsy surgery in selected cases
Glaucoma management (medical or surgical) - critical given the risk of vision loss if undiagnosed/untreated
Laser therapy can improve the cosmetic appearance of the port-wine stain, though does not affect the neurological or ocular disease course

Port-wine stain (trigeminal distribution), glaucoma, seizures/epilepsy, stroke-like episodes, hemiparesis, developmental delay (variable, related to the extent of neurological involvement)

Severity is highly variable depending on the extent of the mosaic mutation - ranging from an isolated facial port-wine stain with no neurological involvement to severe, treatment-refractory epilepsy with significant developmental impact

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