Polymorphism in IgA nephropathy

Abstract

Summary: IgA nephropathy (IgAN) is polyphormic in its clinical manifestation, course and prognosis. Patients with isolated IgA deposit in glomeruli tend to have a high incidence of macroscopic haematuria and carry a better prognosis. In contrast, patients with deposits of IgA and IgG and IgM have a higher incidence of nephrotic syndrome and hypertension. In parallel, patients with IgA and IgG and IgM tend to have more glomerulosclerosis and tubulointestitial lesions. Recently, the angiotensin converting enzyme (ACE) gene polymorphism and its association in disease risk provided interesting exploration leading us to speculate about a possible mechanism to explain the variation in the rate of progression of IgAN; although, the results are still controversial. The variability of plasma ACE concentration has been shown to be associated with an insertion/deletion polymorphism. The frequencies of ACE genotype in 177 Chinese patients with IgAN has been observed. We found that patients with IgAN showed a higher frequency of DD genotype than normal population. In contrast to the previous reports, we did not find any association between ACE genotype and the rate of progression of IgAN. As different genotypes of IL‐1 receptor antagonist (IL‐1 ra) are also responsible for the circulating levels of IL‐1 ra, the polymorphism of IL‐1 ra gene has been analyzed in 100 IgAN patients. There was no significant difference in the frequency of IL1RN*2 allele between normal subjects and IgAN. However, patients with recurrent macroscopic haematuria showed a higher carriage rate of IL1RN*2. Hereditable factors, in combination with a number of recognized environmental risk factors, are important determinants of the pathogenesis and natural history of IgAN. The notion that the gene polymorphism might be responsible for the clinical features and progression of IgAN is both intriguing and provocative. The lessons from previous multiple small size studies have produced conflicting results illustrating the need for observation of large numbers of cases in further studies to verify these observed associations.