LAUSR

BACKGROUND Congenital mirror movements (CMM) are involuntary movements on one side of the body that mirror intentional movements on the opposite side, which persist in adult life. While mutations in DCC, RAD51, NTN1 and other genes have been associated with CMM, recent evidence suggests tubulinopathies, including TUBB3 mutations, may also contribute. CASES An 11-year-old girl with developmental delay and CMM was evaluated, along with her mother and sibling via clinical assessments, neuroimaging, and genetic analysis. Diffusion tensor imaging (DTI) was used to assess corticospinal tract abnormalities. A heterozygous TUBB2B variant was identified in all three affected individuals. DTI revealed reduced corticospinal tract decussation, similar to findings in other genetic causes of CMM. CONCLUSIONS This study highlights new phenomenology of congenital mirror movements associated with TUBB2B-related tubulinopathy, highlighting the role of TUBB2B mutations in neuronal migration, expanding the genetic spectrum of congenital mirror movements.