BRCA1 and neonatal-onset encephalopathy with rigidity and seizures: <h4>Background</h4>Biallelic BRCA1-associated ataxia telangiectasia mutated activator 1 (<i>BRAT1</i>) gene mutations can result in lethal neonatal rigidity and multifocal seizure syndrome (RMFSL), characterized by refractory epilepsy, hypertonia, autonomic dysfunction, and early death.