<prompt> The pathognomonic feature of classic alpo syndrome is:Lenticonus and hematuriaHematuria and sensorineural hearing lossSensorineural hearing loss and lenticonusHematuria and hyperextensibility of joints  <response>: The diagnosis of classic alpo syndrome is based on X-linked inheritance of hematuria, sensorineural hearing loss, and lenticonus. The lenticonus together with hematuria is pathognomonic of classic Alpo syndrome. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Pages 3213-14 