Takeaway
Homozygous and heterozygous STXBP1 mutations share the three main clinical encephalopathy features, despite producing divergent cellular effects; however, homozygous mutant L446F leads to distinct symptoms, characteristic of Lennox-Gastaut syndrome.
Why this matters
Increasing understanding of heterogeneity between homozygous and heterozygous disease mutations will help unveil underlying disease mechanisms, which is crucial for developing therapeutic strategies.