Polymorphisms in the promoter region and at codon 54 of the MBL2 gene are not associated with IgA nephropathy

Background. IgA nephropathy (IgAN) occurs sporadically in unrelated individ uals. Several different polymorphic genes have been investigated in recent years in order to demonstrate their possible association with IgAN. Three r ecent, different studies with conflicting conclusions have discussed the ro le of the mannose binding lectin (MBL), a serum lectin involved in natural immunity, in the IgAN pathogenesis by examination of MBL deposits in biopsi es. In the present study we investigated several polymorphisms of the MBL g ene located in the promoter region and in the first exon. Methods. MBL polymorphism detection was performed in 12. Italian patients w ith familial IgA nephropathy and in 138 Italian patients with the sporadic form of the disease. The polymorphisms in the MBL2 promoter region and in t he exon 1 were investigated, respectively, by direct sequencing and by ampl ification refractory mutation system-polymerase chain reaction on genomic D NA collected from peripheral blood. Seventy-four unrelated healthy subjects matched for ethnic origin were used as controls. Results. Allelic and genotypic frequencies of the polymorphisms at position -550, -328, -221 and at codon 54 did not show any differences between pati ents and controls. Similar frequency distributions of these polymorphisms w ere also found in the subgroups of IgAN patients subdivided according to th e clinical manifestations and the progression of the disease. Conclusions. This study indicates that the analysed polymorphisms of the MB L gene do not appear to be primarily involved in the susceptibility and sev erity of IgAN.