OBJECTIVETo investigate the relationship of disease severity with angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and serum ACE activity in preterm infants during the first 7 days of life.

METHODSACE genotypes were determined in 85 preterm infants admitted to the neonatal intensive care unit (NICU). Serum ACE activity was measured and disease severity was evaluated by the Neonatal Critical Score (draft) 1, 3 and 7 days after birth.

RESULTSOf the 85 preterm infants, DD genotype was found in 19 cases, ID genotype in 34 cases and II genotype in 32 cases. On the 1st day of life, serum ACE activity in the DD genotype (33.42+/-7.93 U/L) and the ID genotype groups (31.53+/-7.56 U/L) were significantly higher than that in the II genotype group (25.53+/-7.56 U/L) (P<0.01). After 3 and 7 days of life, serum ACE activity decreased in the three groups, but the DD genotype group remained the highest ACE activity, followed by the ID genotype and the II genotype groups. On the 1st day of life, the critical score of the DD genotype group (87.37+/-8.30) was lower than the ID genotype (95.82+/-5.85) and the II genotype groups (95.88+/-6.85) (P<0.01). On the 3rd day, the critical score of the DD genotype group was still lower than the ID genotype group (92.95+/-7.10 vs 96.94+/-5.85) (P<0.05).

CONCLUSIONSACE gene I/D polymorphism may be associated with the disease severity in preterm infants. The DD genotype carriers present more severe disease status, with higher serum ACE activity. Although the disease status can influence serum ACE activity, serum ACE activity is determined by the ACE genotype.