Two Boys, Two Custom Drugs: Gene-Targeted Medicine Cuts Seizures in Rare Epilepsy

Individually designed antisense drugs reduced seizures by 26% and 90% in two boys with a rare genetic epilepsy, testing whether n-of-few medicine can work.

Two parallel single-patient studies, published 21 July 2026 in Nature Medicine, treated a 9-year-old boy and a 14-year-old boy with SCN2A-related developmental and epileptic encephalopathy. Each received an individualized antisense oligonucleotide (ASO) designed for his own genetics. The trial is registered as NCT06314490.

The design is precise. SCN2A variants are among the most common genetic causes of these encephalopathies, accounting for 1–2% of cases. The ASOs were built to be allele-selective: they target heterozygous intronic single-nucleotide polymorphisms so that the mutant copy of the gene is reduced while the healthy copy is preserved. One patient saw a 26% reduction in seizure frequency, the other a 90% reduction. Both cut back on other medications and showed neurodevelopmental gains, and neither had ASO-related serious adverse events.

Why it matters for access: the hard part of ultra-rare disease is that no single patient supports a commercial drug program. A repeatable method for designing allele-selective ASOs against a common target gene points toward a template — one platform, many custom drugs — that could bring treatment to diseases that would otherwise never get one. A separate cohort of infants found 16% carried SNPs compatible with this approach, suggesting the method could reach more than these two children.

The caveats are large. This is two patients, one each. The findings are preliminary, efficacy measures were tailored to each child's phenotype, and long-term follow-up is needed to confirm any disease-modifying effect.

Source: Nature Medicine