CTBP1 and hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome: There are 14 reported cases of HADDTS with a heterozygous mutation in the CTBP1 gene; 13 individuals carry the missense mutation c.991C → T [W342 (mutant allele)], and one individual carries the 2-base pair deletion c.1315_1316del CA) (Acosta-Baena et al., 2022).