A syndrome characterized by Lentigines (LENTIGO); Electrocardiographic conduction abnormalities; Ocular HYPERTELORISM; PULMONARY STENOSIS; Abnormal genitalia; Retardation of growth; and Deafness (HEARING LOSS, SENSORINEURAL). It is caused by mutations of the PTPN11 gene which codes for non-receptor PROTEIN TYROSINE PHOSPHATASE, type 11. The clinical features of LEOPARD syndrome overlap those of NOONAN SYNDROME, also caused by mutations in PTPN11, as well as those of NEUROFIBROMATOSIS 1. The syndrome has also been associated with mutations in the NF1 gene (GENES, NEUROFIBROMATOSIS 1). (J Med Genet 2002 Aug;39(8):571-4).