De novo genetic variant in epileptic encephalopathy: Importance of specific diagnosis

Introduction: Early infantile epileptic encephalopathies (EIEE) are rare syndromes that affect neurological development. The etiology has been uncertain for a long time, but advances in genetics have identified numerous associated genes. Variants in the CYFIP2 gene have been linked to EIEE. Clinical case: An 11-year-old female born at term without complications, with microcephaly, synophrys, and short neck. No relevant family history. At one month, she developed generalized seizures and delayed neurodevelopment, progressing to severe spastic quadriparesis, requiring gastrostomy and tracheostomy, with paroxysmal discharges on electroencephalogram. She received multiple anticonvulsant medications and ketogenic therapy. Complete individual exome sequencing and analysis of deletions and duplications were requested. Individual complete exome + deletions and duplications analysis (CNV) identified a probably pathogenic heterozygous variant in the CYFIP2 gene variant c.259C>T (p.Arg87Cys) missense type, allelic ratio (VAF) 0.45. The results of this molecular study support the diagnosis of developmental and epileptic encephalopathy de novo. Discussion: Developmental and epileptic encephalopathy (EED) disorders are severe conditions that begin in childhood, characterized by epileptic seizures, abnormalities in the electroencephalogram, and deterioration of neurodevelopment. Genetic EEDs are associated with variants in various genes related to cellular and neuronal functions. The CYFIP2 gene, on chromosome 5q33.3, encodes protein 2 that interacts with FMRP (fragile X mental retardation protein), playing a crucial role in neurological development. De novo variants, such as nonsense mutations and truncation in CYFIP2, are associated with intellectual disability, seizures, and muscle hypotonia. Advancements in genomics are improving the understanding of epilepsy, impacting targeted treatment, prognosis, and patient counseling. Childhood epilepsy has a heterogeneous genetic basis, and some patients without previous diagnosis can now receive one, crucial for the implementation of precision medicine.