CTBP1 and hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome: HADDTS is an extremely rare autosomal dominant disorder caused by a disruptive pathogenic variant of CTBP1. Fourteen cases of pathogenic variants in the CTBP1 gene have been reported globally, in such cases hypotonia, ataxia, developmental delay and dental enamel defects have long been recognized as the core symptoms.