Missense Variant Met119Val in ACTB in a Patient with Baraitser-Winter Syndrome Type 1 and Mild Intellectual Disability.

Introduction: The Baraitser-Winter syndrome (BRWS) is a rare condition characterized by multiple congenital anomalies and developmental delay. Most cases present moderate to severe global delay and intellectual disability. The etiology of BRWS is heterogeneous, caused by heterozygous gain-of-function variants in ACTB or ACTG1 genes.

Case report: Here we report on a Brazilian female patient with dysmorphic craniofacial features of the BRWS, oligodontia, partial agenesis of the corpus callosum, pineal cyst, cervical cystic hygroma, pterygium colli, axillary pterygium, duplicated left hallux, seizures, and mild developmental delay. Sanger sequencing of the ACTB gene showed the heterozygous missense variation NM_001101.5 (ACTB):c.355A>G (p.Met119Val).

Conclusion: The clinical findings are compatible with the diagnosis of BRWS type 1. Our case includes oligodontia as a new feature of the BRWS type 1 phenotype. Functional study of the variant here described could contribute to elucidate the pathogenetic pathway that results in the severe craniofacial phenotype associated with mild developmental delay.