Pathogenic variants in NACC1 have recently been associated with an autosomal dominant neurodevelopmental disorder with epilepsy, cataracts, feeding difficulties, and delayed brain myelination (OMIM #617393). Other clinical features include microcephaly, extreme irritability, failure to thrive, stereotypic hand movements, and developmental delays and/or intellectual disability. All seven individuals reported thus far have an identical, recurrent, de novo heterozygous variant called c.892C>T (p.Arg298Trp). One of the seven individuals is mosaic for this variant and has a milder phenotype.