Intellectual Developmental Disorder with Macrocephaly, Seizures, and Speech Delay, is also known as iddmssd. An important gene associated with Intellectual Developmental Disorder with Macrocephaly, Seizures, and Speech Delay is PAK1 (P21 (RAC1) Activated Kinase 1). Affiliated tissues include eye and brain, and related phenotypes are seizure and frontal bossing