This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics And Genetic Disorders, Subject name: Pediatrics
The structural abnormality of chromosome in which one arm is lost and remaining arm is duplicated is called: 
Select and explain. 
A. Ring chromosome, B. Isochromosome, C. Translocation, D. Mutation
B: Isochromosome
Answer: B: Isochromosome 
Explanation: b. Isochromosome(Ref: Nelson's 20/e p 590', Ghai 8/e p 637)Iso-chromosome results when 1 arm of a chromosome is lost and the remaining arm is duplicated or when the axis of division occurs perpendicular to the normal axis of division.