Hydrocephalus, calcification of the basal ganglia, encephalocele, absent olfactory lobes, cranial nerve paralysis, and seizures. Occasional defects may include patent ductus arteriosus, ventricular septal defect, and atrial septal defect. Polycystic or horseshoe kidneys, hydronephrosis and ureteral stenosis may be associated. Transmitted as an autosomal recessive trait. Capillary hemangiomas of the midface, forehead, and ears.
Melanoma occurs in some cases.