A Girl with PRRT2 Mutation Presenting with Benign Familial Infantile Seizures Followed by Autistic Regression.

Benign familial infantile seizure (BFIS) is an autosomal dominant infantile-onset epilepsy syndrome with a typically benign prognosis. It is commonly associated with heterozygous mutations of the gene located on chromosome 16p11.2. The frameshift heterozygous mutation (c.649dupC, p.Arg217Profs8) in is responsible for the majority of BFIS cases. In this report, we present a rare case of a girl with a confirmed clinical and genetic diagnosis of BFIS due to a frameshift heterozygous mutation in (c.649dupC). She exhibited typical neurodevelopment until 15 months of age, followed by an unexpected severe autistic regression. In addition to BFIS, mutations are also associated with paroxysmal kinesigenic dyskinesia (PKD) and infantile convulsions and paroxysmal choreoathetosis (ICCA), indicating a complex genotype-phenotype heterogeneity in mutations. This clinical observation highlights the possibility that BFIS patients with mutations may not always have a benign neurodevelopmental prognosis, emphasizing the need for long-term clinical follow-up.