This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics, Subject name: Medicine
[{'content': "The following are single gene disorders except \nSelect and explain. \nA. Hemochromatosis, B. Cystic fibrosis, C. William's syndrome, D. Huntington's disease", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Single-Gene Disorders with Nonclassic Inheritance It has become increasingly evident that transmission of ceain single-gene disorders does not follow classic Mendelian principles. This group of disorders can be clas- sified into four categories: * Diseases caused by trinucleotide-repeat mutations * Disorders caused by mutations in mitochondrial genes * Disorders associated with genomic imprinting * Disorders associated with gonadal mosaicism Disorders include : hemochromatosis,cystic fibrosis, Huntington disease Ref Robbins 9/e pg 168', 'role': 'assistant'}]