Hypotonia, Ataxia, Developmental Delay, and Tooth Enamel Defect Syndrome, also known as haddts, is related to hypotonia and contractures, pterygia, and spondylocarpotarsal fusion syndrome 1a. An important gene associated with Hypotonia, Ataxia, Developmental Delay, and Tooth Enamel Defect Syndrome is CTBP1 (C-Terminal Binding Protein 1). Affiliated tissues include eye, and related phenotypes are ataxia and hypotonia