Children with SPG47 present with progressive spastic paraplegia, global developmental delay and later intellectual disability, secondary microcephaly, early-onset epilepsy and cerebral dysgenesis including thinning of the corpus callosum (Ebrahimi-Fakhari et al, 2020; Ebrahimi-Fakhari et al, 2021a; Jordan et al, 2021). The gene discussed is AP4B1; the disease is Global developmental delay.