We present a case of lethal neonatal rigidity and multifocal seizure syndrome (RMFSL) in an early-term female infant born to non-consanguineous parents. RMFSL is a recently discovered autosomal recessive disease caused by the BRAT1 gene mutations. The BRAT1 gene encodes the BRCA1-associated protein required for ATM activation-1, a protein that interacts with BRCA1 and ATM to initiate DNA repair in response to DNA damage. The exon sequence revealed biallelic deletions of exon 1-2 of the BRAT1 gene in our patient. There are only a few cases of RMFSL reported in the literature, and all of them have died before two years, mostly in the first six months of life. Our patient died at the age of 74 days.