This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Pathology
[{'content': 'In thin basement membrane disease, the defect is in \nSelect and explain. \nA. a1 and a2 chains of type IV collagen, B. a3 and a4 chains of type IV collagen, C. a1 and a2 chains of type VI collagen, D. a3 and a4 chains of type VI collagen', 'role': 'user'}, {'content': 'Answer: B \nExplanation: TBM disease (also known as benign familial hematuria and thin basement membrane nephropathy) is, along with IgA nephropathy, the most common cause of blood in the urine without any other symptoms. The only abnormal finding in this diseaseis a thinning of the basement membrane of the glomeruli (filters) in the kidneys. Refer robbins 9/e', 'role': 'assistant'}]