Major brain malformations: corpus callosum dysgenesis, agenesis of septum pellucidum and polymicrogyria in patients with BCORL1 -related disorders

Objective BCORL1 , a transcriptional co-repressor, has a role in cortical migration, neuronal differentiation, maturation, and cerebellar development. We describe BCORL1 as a new genetic cause for major brain malformations. Methods and results We report three patients from two unrelated families with neonatal onset intractable epilepsy and profound global developmental delay. Brain MRI of two siblings from the first family depicted hypoplastic corpus callosum and septal agenesis (ASP) in the older brother and unilateral perisylvian polymicrogyria (PMG) in the younger one. MRI of the patient from the second family demonstrated complete agenesis of corpus callosum (CC). Whole Exome Sequencing revealed a novel hemizygous variant in NM_021946.5 ( BCORL1 ):c.796C>T (p.Pro266Ser) in the two siblings from the first family and the NM_021946.5 (BCORL1): c.3376G>A; p.Asp1126Asn variant in the patient from the second family, both variants inherited from healthy mothers. We reviewed the patients’ charts and MRIs and compared the phenotype to the other published BCORL1 -related cases. Brain malformations have not been previously described in association with the BCORL1 phenotype. We discuss the potential influence of BCORL1 on brain development. Conclusions We suggest that BCORL1 variants present with a spectrum of neurodevelopmental disorders and can lead to major brain malformations originating at different stages of fetal development. We suggest adding BCORL1 to the genetic causes of PMG, ASP, and CC dysgenesis.