What is (are) Miller-Dieker syndrome ?
Miller-Dieker syndrome is a condition characterized by a pattern of abnormal brain development known as lissencephaly. Normally the exterior of the brain (cerebral cortex) is multi-layered with folds and grooves. People with lissencephaly have an abnormally smooth brain with fewer folds and grooves. These brain malformations cause severe intellectual disability, developmental delay, seizures, abnormal muscle stiffness (spasticity), weak muscle tone (hypotonia), and feeding difficulties. Seizures usually begin before six months of age, and some occur from birth. Typically, the smoother the surface of the brain is, the more severe the associated symptoms are.  In addition to lissencephaly, people with Miller-Dieker syndrome tend to have distinctive facial features that include a prominent forehead; a sunken appearance in the middle of the face (midface hypoplasia); a small, upturned nose; low-set and abnormally shaped ears; a small jaw; and a thick upper lip. Some individuals with this condition also grow more slowly than other children. Rarely, affected individuals will have heart or kidney malformations or an opening in the wall of the abdomen (an omphalocele) that allows the abdominal organs to protrude through the navel. People with Miller-Dieker syndrome may also have life-threatening breathing problems. Most individuals with this condition do not survive beyond childhood.