We previously described inherited biallelic variants in the KPTN gene as underlying KPTN-related disorder (KRD), also known as macrocephaly, autistic features, seizures, developmental delay (MASD) syndrome (OMIM 615637), an autosomal recessive neurodevelopmental disorder in nine affected individuals from an extended interrelated family of Ohio Amish background.27 All affected individuals were either homozygous or compound heterozygous for two KPTN founder variants [(p.(Ser259*) and p.(Met241_Gln246dup)]. This evidence concerns the gene KPTN and Global developmental delay.