Walker-Warburg syndrome is a congenital disorder of the central
nervous system involving fatal neurological lesions. Multiple
malformations of the brain, eyes, and muscle tissue distinguish
WWS from similar malformation syndromes. It is also known by the
acronym HARD +/- E syndrome (hydroencephalus, agyri, retinal
dysplasia, plus or minus "e" for encephalocele). Affected
individuals typically show a combination of severe brain, eye,
and muscle defects. Multiple malformations of the brain include
type II lissencephaly, a condition in which the brain lacks
normal convolutions and is unusually smooth without folds.
Eighty-four percent of the babies with WWS have macrocephaly (an
enlarged head). In half of these cases, the macrocephaly is
apparent at birth, and in a quarter of the cases it develops
postnatally. Hydrocephalus, or excessive accumulation of
cerebrospinal fluid around the brain, occurs in 95% of infants
with WWS. This fluid fills abnormally large ventricles or spaces
in the brain. Fifty percent of af