Which one of the following is not true regarding Noonan&;s syndrome

Individuals who have Noonan syndrome have normal chromosome studies. Four genes - PTPN11, SOS1, RADF1and KRAS - are the only genes that are known.Symptoms of Noonan syndrome may include the following: A characteristic facial appearance. Sho stature. Hea defect present at bih (congenital hea defect). A broad or webbed neck. Minor eye problems such as strabismus in up to 95 percent of individuals. Bleeding problems such as a history of abnormal bleeding or bruising. An unusual chest shape with widely-spaced and low set nipples. Developmental delay of varying degrees, but usually mild. In males, undescended testes (cryptorchidism). Reference: GHAI Essential pediatrics, 8th edition