Angiotensin converting enzyme gene polymorphism in lupus nephritis

Background. Lupus nephritis is one of the most serious complications in pat ients with systemic lupus erythematosus (SLE). Both immunological and nonim munological factors are known to be involved in the progression of this typ e of glomerulopathy. The present study was designed to clarify the clinicop athological significance of ACE (angiotensin converting enzyme) gene polymo rphism in patients with lupus nephritis. Methods. Genomic DNA was obtained from 25 biopsy-proven Japanese lupus neph ritis patients. Insertion/deletion (ID) polymorphism of the ACE gene was de termined using PCR (polymerase chain reaction). Association between ACE gen e polymorphism and clinicopathological factors was evaluated in a cross-sec tional study. Results. The frequency of insertion/insertion (II)! ID and deletion/deletio n (DD) in ACE genotypes was 44, 52, and 4%, respectively. Patients were div ided into two groups according to the presence or absence of D allele, name ly 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 associati on with hypertension, or decreased renal function. ACE genotypes were not a ssociated with the degree of proteinuria or incidence of nephrotic syndrome . The frequency of the World Health Organization (WHO) class IV renal lesio n, 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 b e related to higher levels of serum ACE activity in lupus nephritis, althou gh its clinical significance still remains to be determined.