The main features of the characteristic facies are
epicanthal folds, flat nasal bridge, anteverted nostrils, blue stellate iris, and
mandibular hypoplasia associated with dental anomalies and a tendency to keep
mouth open. Patients also have a typical hoarse voice. Neonatal hypercalcemia is common and can
lead to nephrocalcinosis. The main cardiovascular anomaly is supravalvular aortic
stenosis, but other anomalies can be present. Sudden death is frequent in patients with
coronary artery stenosis or severe biventricular outflow tract obstruction and is a result
of myocardial ischemia, decreased cardiac output, and arrhythmia. The overall
incidence of sudden death over a 30-year period is reported to be 3%. Patients usually
have a friendly personality and normal language skills despite their mental retardation
(IQ 40 to 80). During infancy, they may present with hypotonia, which may remain the same
or convert to hypertonia at an older age. As the patients grow older, they may develop
hypertension, progressive joint limitations, recurrent urinary tract infections, obesity,
diverticulosis, and cholelithiasis. Other features include hypoplastic nails,
clinodactyly, hallux valgus, pectus excavatum, umbilical hernia, and a small penis.