Transcriptional corepressor CTBP1 in the heterozygous condition with a specific R342W mutation causes prominent neurodevelopmental manifestations, including hypotonia, ataxia, and developmental delays in HADDTS patients (Acosta-Baena et al., 2022; Beck et al., 2016; Beck et al., 2019; Vijayalingam et al., 2020). Here, CTBP1 is linked to Global developmental delay.