Rigidity and Multifocal Seizure Syndrome, Lethal Neonatal (RMFSL) (OMIM# 614498) is a rare and recently characterized epileptic encephalopathy that is related to variants in the BRAT1 gene (Breast Cancer 1-associated ataxia telangiectasia mutated activation-1 protein). In this report, an RMFSL case, who died in the 10th month of the life, with rigidity, drug-resistant myoclonic seizures in the face and extremities, with, significant motor delays is presented. The exon sequence was determined and a new homozygous variant (C.2230_2237dupAACATGC) was detected. This RMFSL case with a homozygous variant in the BRAT1 gene, is the fourth one in the literature and the first one being reported from a Turkish family.