Urinary excretion of glomerular basement membrane antigens in Alport's syndrome. A new diagnostic approach.

Alport's syndrome is defined by the combination of hereditary nephropathy and neurosensory deafness, and is diagnosed from the family history combined with renal electron microscopy. Immunoelectrophoresis of the urine of 8 of 12 children suspected of Alport's syndrome showed a precipitation line moving into the beta-zone, applying an antiglomerular basement membrane antibody derived from an immunised rabbit. All patients who showed the typical pattern of Alport's syndrome on renal electron microscopy were among the 8 cases whose urine gave this immunoelectrophoresis pattern. Additionally, 5 of the mothers of the 8 children excreted the same antigen in their urine. The urine of 30 healthy children and of 10 patients with the idiopathic nephrotic syndrome did not show the presence of this antigen. This characteristic sign of Alport's syndrome may therefore be useful for its detection.