<prompt> In thin basement membrane disease, the defect is ina1 and a2 chains of type IV collagena3 and a4 chains of type IV collagena1 and a2 chains of type VI collagena3 and a4 chains of type VI collagen  <response>: 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 9e 