Dandy-Walker Malformation With Postaxial Polydactyly

Clinical Features

The Dandy-Walker malformation (220200) is characterized by posterior fossa cyst continuous with the fourth ventricle, presumably representing agenesis of the foramina of Magendie and Luschka; partial or complete absence of the cerebellar vermis; and facultative hydrocephalus. Pierquin et al. (1989) reported male and female sib fetuses with the combination of DWM and postaxial polydactyly and suggested that the sibs reported by Egger et al. (1982) had the same syndrome, a disorder distinct from other conditions in which DWM has sometimes been observed, such as the Mohr syndrome (252100) and the Joubert-Boltshauser syndrome (JBTS; 213300). Pierquin et al. (1989) stated that the polydactyly seen with these other conditions is preaxial. The sibs reported by Egger et al. (1982) as having JBTS had postaxial polydactyly of the hands and feet, tachypnea up to 95 respirations per minute, and by computed tomography hypoplasia of the vermis, associated in 1 sib with a cyst of the fourth ventricle, consistent with DWM. One sib had fleshy tumors of the tongue.

Cavalcanti and Salomao (1999) described a male infant, the product of first-cousin parents, in whom ultrasonography at 34 weeks' gestation showed polyhydramnios, posterior fossa cyst, cerebellar vermis agenesis, postaxial polydactyly, and discrete dilatation of the right kidney pelvis. Dysmorphism noted after birth included large head with dolichocephaly, broad and depressed nasal bridge, low-set ears, microretrognathia, and tetramelic postaxial polydactyly. Cerebral ultrasonography in the first days of life showed large posterior fossa cyst, cerebellar hypoplasia, and normal supratentorial ventricular system.

Passalacqua et al. (2013) reported an infant with macrocephaly, frontal bossing, small palpebral fissures, flat nasal bridge, and bilateral postaxial polydactyly of the hands. MRI of the brain showed dilatation of the lateral and third ventricles, a thin corpus callosum, and a Dandy-Walker malformation. Echocardiography showed a patent ductus arteriosus, moderate aortic valve dysplasia, and mild aortic stenosis, which later progressed to severe stenosis. Ophthalmologic examination showed chorioretinal atrophy, posterior embryotoxon, and pale optic nerves. The authors suggested that their patient had the same condition as that described by Pierquin et al. (1989), although the cardiac and ophthalmologic manifestations had not previously been described. They proposed that this condition be called Pierquin syndrome.