A patient with the de novo STXBP1 c.416C > T, p.(P139L) missense pathogenic variant in exon 6 presented with neonatal-onset epilepsy and by age 6 weeks showed a mixture of tonic and intermittent focal seizures controlled with phenobarbital by 4 months, global DD, ataxia by 6 years, head nodding stereotypies by age 7, dystonic posturing of her legs and a prominent dystonic tremor of her upper limbs at age 9. Here, STXBP1 is linked to cerebellar ataxia.