Angiotensin converting enzyme gene polymorphism in lupus nephritis

Background. Lupus nephritis is one of the most serious complications in patients with systemic lupus erythematosus (SLE). Both immunological and nonimmunological factors are known to be involved in the progression of this type of glomerulopathy. The present study was designed to clarify the clinicopathological significance of ACE (angiotensin converting enzyme) gene polymorphism in patients with lupus nephritis. Methods. Genomic DNA was obtained from 25 biopsy-proven Japanese lupus nephritis patients. Insertion/deletion (ID) polymorphism of the ACE gene was determined using PCR (polymerase chain reaction). Association between ACE gene polymorphism and clinicopathological factors was evaluated in a cross-sectional study. Results. The frequency of insertion/insertion (II)! ID and deletion/deletion (DD) in ACE genotypes was 44, 52, and 4%, respectively. Patients were divided into two groups according to the presence or absence of D allele, namely II and ID + DD. Serum ACE activities were significantly higher in the ID + DD group than in the II group (12.7 +/- 3.2 vs. 7.83 +/- 1.9 IU/l, p = 0.002). There was no difference between the two groups in terms of association with hypertension, or decreased renal function. ACE genotypes were not associated with the degree of proteinuria or incidence of nephrotic syndrome. The frequency of the World Health Organization (WHO) class IV renal lesion, which is the most severe form of nephritis, was not associated with ACE genotype. Conclusions. These findings suggest that the D allele of the ACE gene may be related to higher levels of serum ACE activity in lupus nephritis, although its clinical significance still remains to be determined.