NEDAMSS or neurodevelopmental disorder with regression, abnormal movements, loss of speech and seizures, is a progressive neurological syndrome clinically presenting as moderate intellectual disability, thin body habitus, microcephaly, seizures, ataxia, progressive muscle weakness, and speech impairment.^[1] NEDAMSS was initially described as mutations in the intronless interferon regulatory factor 2 binding protein-like (IRF2BPL) gene in 2018 .^[2][3][4][5]

Individuals diagnosed with NEDAMSS often clinically present heterogeneously, and case reports about specific mutations in genes encoding for the IRF2BP family of transcriptional regulators are ongoing and sparse.

A case report of an individual diagnosed with NEDAMSS published in 2025 by Kristiansen and colleagues described the phenotypic presentation of NEDAMSS patients sharing significant DSM-5 characteristics with catatonia. This 14-year-old boy presented with mildly delayed motor and speech milestones during early childhood, and unremarkable neurological exams at 13 and 14 years of age.^[5] At 14, this patient began to show mental deterioration and symptoms of muscle stiffness, tremor, staring, hypomimia with facial contractions, and lack of responsiveness after a stressful life event. This individual then withdrew socially and decreased his food and fluid intake that corresponded with increased muscle stiffness. Lorazepam treatment alleviated some of the muscle symptoms but increased drowsiness prompted physicians to decrease the dose, which caused worsening of symptoms.