Lanoue V, Chai YJ, Brouillet JZ, Weckhuysen S, Palmer EE,
Collins BM, Meunier FA. STXBP1 encephalopathy: Connecting neurodevelopmental
disorders with α-synucleinopathies? Neurology. 2019 Jul 16;93(3):114-123.
Abstract
De novo pathogenic variants in STXBP1 encoding syntaxin1-binding
protein (STXBP1, also known as Munc18-1) lead to a range of early-onset
neurocognitive conditions, most commonly early infantile epileptic
encephalopathy type 4 (EIEE4, also called STXBP1 encephalopathy), a severe form
of epilepsy associated with developmental delay/intellectual disability. Other
neurologic features include autism spectrum disorder and movement disorders.
The progression of neurologic symptoms has been reported in a few older
affected individuals, with the appearance of extrapyramidal features,
reminiscent of early onset parkinsonism. Understanding the pathologic process
is critical to improving therapies, as currently available antiepileptic drugs
have shown limited success in controlling seizures in EIEE4 and there is no precision
medication approach for the other neurologic features of the disorder. Basic
research shows that genetic knockout of STXBP1 or other presynaptic proteins of
the exocytic machinery leads to widespread perinatal neurodegeneration. The
mechanism that regulates this effect is under scrutiny but shares intriguing
hallmarks with classical neurodegenerative diseases, albeit appearing early
during brain development. Most critically, recent evidence has revealed that
STXBP1 controls the self-replicating aggregation of α-synuclein, a presynaptic
protein involved in various neurodegenerative diseases that are collectively
known as synucleinopathies, including Parkinson disease. In this review, we
examine the tantalizing link among STXBP1 function, EIEE, and the
neurodegenerative synucleinopathies, and suggest that neural development in
EIEE could be further affected by concurrent synucleinopathic mechanisms.
At our institution, Gillette Children's Specialty Healthcare, I'm aware of 5 patients with this diagnosis.
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