Two boys, ages 9 and 14, with SCN2A gain-of-function mutations and daily seizures received individualized antisense oligonucleotide (ASO) therapy in a 2026 Nature Medicine study by Olivia Kim-McManus et al. The 9-year-old received 12 intrathecal doses over 24 months and was able to stop taking phenytoin entirely. The 14-year-old received 8 doses over 16 months and went from an average of two seizures per day to zero.
The critical engineering problem here is allele specificity. SCN2A mutations typically affect only one copy of the gene, so standard antisense therapy risked silencing healthy mRNA alongside the mutant transcript. The team designed ASOs tailored to each patient's specific mutant allele, leaving the functional copy untouched. That design decision, and how they validated it, is the technical core worth reading in full.
Beyond seizure reduction, both patients showed measurable gains in language, motor control, and behavior. The 15-year-old walked unassisted after previously being unable to. ASOs persist in cells long enough to make dosing intervals practical. The open question the paper raises: whether early intervention in affected infants could redirect neurodevelopment entirely. Parallel CRISPR-based gene correction work in mouse models is already underway, published separately in Nature.
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