Congenital mental retardation with Dandy-Walker
malformation of the cerebellum and fourth ventricle. Associated with basal ganglia disease and seizures.
Dandy-Walker Malformation with Mental Retardation; Basal
Ganglia Disease and Seizures; X-Linked Mental Retardation Syndromic-5 with
One of the nonspecific X-linked mental retardation
Four-generation family of Dutch descent. The incidence
of X-linked mental retardation is estimated to be 1:546 live male births,
with a carrier frequency of 1:410 female births.
X-linked transmission. This disease gene map
locus is at Xq25-q27.
Clinical features (mental retardation, abnormal
neurological signs) together with radiological findings of dilatation of the
fourth ventricle. Necropsy demonstrates iron accumulation in the basal
ganglia with neuroaxonal dystrophy.
The major symptom is mental retardation. The
phenotypic features are variable and nonspecific. Other key manifestations
include early hypotonia with progression to spasticity and contractures,
choreoathetosis, seizures, a long, narrow face with coarse features, cystic
enlargement of the fourth ventricle with cerebellar hypoplasia (Dandy-Walker
The patient's history should be
evaluated in relation to seizures and, in particular, current anticonvulsant
therapy and complications resulting from the therapy. In patients with
raised intracranial pressure, no sedative premedication should be
Unwillingness or inability to cooperate
because of fear, anxiety, and incapacity to communicate in addition to the
degree of mental retardation.
Pharmacological triggers that
potentiate occurrence of seizures are to be avoided (enflurane with
hypocapnia, methohexital, ketamine). Drugs that potentially cause or
exacerbate extrapyramidal symptoms (e.g., phenothiazines, butyrophenone
derivatives including droperidol, and metoclopramide) should be avoided.
Ketamine has been shown to be effective as a monotherapy in hypotonic
children for minor surgical procedures.
Pettigrew AL, Jackson LG, Ledbetter DH: New X-linked mental retardation
disorder with Dandy-Walker malformation, basal ganglia disease, and
seizures. Am J Med Genet 38(2-3):200, 1991.