Miller-Dieker syndrome

Overview
Miller-Dieker syndrome is a disease characterised by a developmental defect of the brain, caused by incomplete neuronal migration.

Presentation
The brain is smooth (also known as lissencephaly), has an absence of sulci and gyri, has a cerebral cortex 4 layers thick instead of 6 and shows microcephaly. There is a characteristic facial appearance, delayed growth and mental development, and multiple abnormalities of the brain, heart, kidney and gastrointestinal tract.

Failure to thrive, feeding difficulties, seizures and decreased spontaneous activity are often seen, and death tends to occur in infancy and childhood.

Genetics
Originally thought to be an autosomal recessive disorder, it is now known to be an autosomal dominant disorder, and a haploinsufficiency of one or more genes on chromosome 17p.

The disease arises from the deletion of part of 17p (which includes both the LIS1 and 14-3-3 epsilon gene), leading to partial monosomy. There may be unbalanced translocations (ie 17q:17p or 12q:17p), or the presence of a ring chromosome 17.

Diagnosis
The disease may be diagnosed by cytogenetic techniques, testing for a microdeletion at LIS1.

Eponym
It is named for JQ Miller and H. Dieker.