A recent cohort of 23 individuals from 12 families with sphingomyelin phosphodiesterase 4, neutral membrane (SMPD4; Magini et al., 2019) variants displayed phenotypes such as microcephaly cerebellar hypoplasia, delayed or hypomyelination of the brain, and severe developmental delay (7/7). This evidence concerns the gene SMPD4 and Global developmental delay.