This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Pathology
[{'content': "NOT a mutation in Down's syndrome \nSelect and explain. \nA. Mosaicism, B. Robersonian translocation, C. Maternal non disjunction, D. VNTR's", 'role': 'user'}, {'content': "Answer: D \nExplanation: (D) VNTR's# A Variable Number Tandem Repeat (or VNTR) is a location in a genome where a short nucleotide sequence is organized as a tandem repeat is associated with major psychiatric disorders.> Trisomy 21 also known by the karyotype 47, XX+21 for females and 47,XY,+21 for males.> The extra chromosome 21 material may also occur due to a Robertsonian translocation in 2-4% cases. In this situation, the long arm of chromosome 21 is attached to another chromosome, often chromosome 14.", 'role': 'assistant'}]