Objective In order to explore the possibility that genetic predisposition to dysfunction of mucosal immunity and the IgA processing pathway plays a role in the pathogenesis of mesangial IgAl deposition in IgAN, we examined the possible association of the gene polymorphismof plgR in the patients with and without IgAN. Subjects and Methods Genomic DNAof peripheral blood cells was isolated from 372 individuals including 172 histologically confirmed IgAN patients. Segments of the plgR gene were

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... mplified and restriction fragment length polymorphism was determined as Al and A2 with and without Pvu II site, respectively. Results The plgR genotype distribution was significantly different between the patients with IgAN and those without IgAN. Allele frequency ofA2 was higher in IgAN than in other renal diseases (Al and A2; 0.516 and 0.484 in IgAN, 0.641 and 0.359 in others, %2=9.84, P=0.0017, Odds ratio=1.71). Moreover, the subjects with A2A2genotype were associated with a relatively low level of serum IgA only in the patients with IgANbut not in other renal diseases. The difference of allele frequencies was moreremarkable in the patients with a serum IgA level of less than 300 mg/dl (Al and A2; 0.439 and 0.561 in IgAN, 0.702 and 0.298 in others, %2=12.44, P=0.0004, Odds ratio=3.01). Conclusion This is the first demonstration of the plgR gene polymorphisms in IgANwhich are associated with its clinical phenotype. Gene polymorphisms of plgR may be candidate genetic markers of susceptibility to IgAN. (Internal Medicine 40: 867-872, 2001)