??? ??? ?? ? ? ?? ?? ??? ????? ??? ?? ??? ???? ??? ???? ?????.????? ??? ????? ???? ????.????? ???? ??? ??? ??? ???? ?????.A chromosomal abnormality consisting from the absence of one of the copies of chromosome seven in somatic cells. [from NCI]Retinoblastoma is a malignant tumor on the acquiring retina that occurs in young children, ordinarily ju