LEOPARD syndrome (LS) is defined by Lentigines, Electrocardiographic abnormalities, Ocular hyperthelorism, Pulmonary valve stenosis, Abnormal genitals, Retarded growth and Deafness, and is caused by heterozygous mutations in the protein tyrosine phosphatase, non-receptor type 11 gene (PTPN11). The gene discussed is PTPN11; the disease is Leigh syndrome.