The localization of HTT at the synapse, its prominent role in both pre- and postsynaptic function, and the finding that synaptic dysfunction occurs before neuronal atrophy and behavioral symptoms in HD (Di Figlia et al., 1995; Sun et al., 2001; Marcora and Kennedy, 2010; Rozas et al., 2011; Barron et al., 2021), led us to investigate whether mHTT affects early developmental properties of synaptogenesis in human neurons. The gene discussed is HTT; the disease is Huntington disease.