Miller–Dieker syndrome, Miller–Dieker lissencephaly syndrome (MDLS), and chromosome 17p13.3 deletion syndrome is a micro deletion syndrome characterized by congenital malformations. Congenital malformations are physical defects detectable in an infant at birth which can involve many different parts of the body including the brain, hearts, lungs, liver, bones, or intestinal tract. MDS is a contiguous gene syndrome – a disorder due to the deletion of multiple gene loci adjacent to one another. The disorder arises from the deletion of part of the small arm of chromosome 17p (which includes both the LIS1 and 14-3-3 epsilon genes), leading to partial monosomy. There may be unbalanced translocations (i.e. 17q:17p or 12q:17p), or the presence of a ring chromosome 17. This syndrome should not be confused with Miller syndrome, an unrelated rare genetic disorder, or Miller Fisher syndrome, a form of Guillain–Barré syndrome. Presentation The brain is abnormally smooth, with fewer folds and grooves. The face, especially in children, has distinct characteristics including a short nose with upturned nares, thickened upper lip with a thin vermilion upper border, frontal bossing, small jaw, low-set posteriorly rotated ears, sunken appearance in the middle of the face, and hypertelorism of eyes. The forehead is prominent with bitemporal hollowing. Children typically also have microcephaly, a wide upper lip, and midface hypoplasia. Characteristics that are not visual include intellectual disabilities, pre- and postnatal growth retardation, epilepsy, and reduced lifespan. Children may also experience breathing problems, dysphagia, feeding problems, hypotonia, spasticity, and muscle stiffness. Failure to thrive, feeding difficulties, seizures and decreased spontaneous activity are often seen. Death usually occurs in infancy and childhood. Multiple abnormalities of the brain, kidneys, and gastrointestinal tract (the stomach and intestines) may occur. Cause MDS is a microdeletion syndrome involving loss of the gene PAFAH1B1 on chromosome 17 which is responsible for the syndrome's characteristic sign of lissencephaly. The loss of another gene, YWHAE, in the same region of chromosome 17 increases the severity of the lissencephaly in patients with Miller–Dieker syndrome. Additional genes in the deleted region are likely to contribute to the varied features of Miller–Dieker syndrome. It may be a random event during the formation of reproductive cells or in early fetal development or due to familial chromosomal rearrangement called chromosomal translocation. In less than 20%, inheritance is through an autosomal dominant pattern. The parent is usually unaffected, but carries a particular chromosomal rearrangement called a balanced translocation, in which no