Transcriptional repressor which plays a role in development of the central nervous system (CNS). In concert with ATXN1 and ATXN1L, involved in brain development. Interacts with ATXN1 and ATXN1L. Found in a complex with ATXN1 and ATXN1L. Expressed in fetal brain. The disease is caused by variants affecting the gene represented in this entry. Expressed in medulloblastoma, a pediatric brain tumor which may arise from the granule cell lineage.