CTBP1 and hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome: In 2016, it was definitively established that variant in the CTBP1 gene, located at chr4:1,205,233–1,242,918 GRCh37/hg19, cause Hypotonia, Ataxia, Developmental Delay, and Dental Enamel Defect Syndrome (HADDTS, MIM:617915) (Beck et al., 2016).