This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitreous and retina, Subject name: Ophthalmology
Hereditary retinoblastomas develop from the following chromosomal deletion? 
Select and explain. 
A. 13 q14, B. 13 p14, C. 14 p13, D. 14 q13
A: 13 q14
Answer: A: 13 q14 
Explanation: 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