This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics of Common Disorders, Subject name: Pediatrics
Down syndrome, All are seen except - 
Select and explain. 
A. t(14:21), B. Trisomy, C. t(11:14), D. t(15:21)
C: t(11:14)
Answer: C: t(11:14) 
Explanation: Ans. is 'c' i.e., t (11:14) [Ref: Nelson 17th/e Chapter 18o In 95% of cases of Down syndrome-trisomy of 21.o Extra chromosome is of maternal in origin,o 1 % have mosaic with some all have 46 chromosome,o 4% have robertsonian translocation.t(13:21)t(14:21)t(15:21)o Very rarely long arm of chromosome 21 is triplicate (Partial trisomy).