The incidence of del(ATM) in Binet A,Binet B and Binet C was 3/20(15%),2/10(20%) and 1/13(7.7%),respectively.

• 10例Binet B期患者中；2例(20%25)存在异常; 13例Binet C期患者中；1例(7.；7%25)存在异常。