Sequencing identified a significant de novo heterozygous missense variant [2] in the gene encoding c-terminal binding protein 1 (CTBP1): CTBP1 (NM_001012614.2): c.991C > T p.(Arg331Trp) as a rare cause of hypotonia, developmental delay and tooth enamel defect syndrome (HADDTS) [2, 3]. The gene discussed is CTBP1; the disease is Global developmental delay.