Abstract
BACKGROUND: The cohesin complex is a multifunctional unit that plays a crucial role in DNA repair, replication, chromosome segregation, and gene expression. Dysfunctions in this complex can lead to a spectrum of developmental disorders collectively known as cohesinopathies. CASE: We retrospectively analysed the clinical data of a 2-year-old boy who was admitted to the hospital with seizures. Genetic testing identified a heterozygous de novo variant in STAG1 at the c.2549G > A (p.Gly850Asp) locus. METHODS: A comprehensive literature review was conducted to summarize previously reported STAG1 variants and their associated clinical features. CONCLUSION: This study expands the molecular spectrum of STAG1 variants. This suggests that genetic testing is highly important, especially for neurodevelopmental disorders with unknown causes. It can facilitate early intervention and guide prenatal diagnosis and genetic counseling.