Hereditary retinoblastomas develop from the following chromosomal deletion?: (A) 13 q14, (B) 13 p14, (C) 14 p13, (D) 14 q13
Answer is A. Retinoblastoma (RB) gene has been identified as 14 band on the long-arm of chromosome 13 (13q14) and is a 'cancer suppressor' or 'antioncogenic' gene.Deletion or inactivation of this protective gene by two mutations (Knudson's two-hit hypothesis) results in the occurrence of retinoblastoma.Ref: Khurana; Comprehensive ophthalmology; 4th edition; Page no: 280