Membranoproliferative glomerulonephritis and alpha 1-antitrypsin deficiency in children.

Two white girls had reduced serum concentration of alpha 1-antitrypsin (alpha-AT), phenotype ZZ, and liver disease. Hepatocytes exhibited the microscopic criteria of alpha-AT deficiency. Hypocomplementemia, elevated circulating immune complexes (patient 1), clinical signs of renal disease, and the histologic findings of membranoproliferative glomerulonephritis (MPGN) type I developed. Immunoglobulin A (but not alpha-AT) was demonstrable immunologically as a component of glomerular deposits in patient 1. Among 53 patients with MPGN but without clinical signs of liver disease, none had Pi type Z. Among 23 patients with phenotype ZZ but without clinical signs of kidney disease, six had abnormal complement protein levels, but the pattern did not resemble that of idiopathic MPGN type I. These results are consistent with the conclusion that MPGN in the two patients reported here is a consequence of their chronic liver disease and is not directly related to the presence of the allelic alpha-AT variant PiZ.