目的：探讨血管紧张素转化酶（angiotensin converting enzyme，ACE）基因插入/缺失（I/D）多态性与ACE水平、危重病评分的关系。方法：确定新生儿重症监护病房（Neonatal Intensive Care Unit，NICU）早产儿ACE基因型，生后第1天、3天、7天分别检测ACE水平并进行危重病例评分。结果：85例早产儿中，DD基因型19例，ID基因型34例，II基因型32例，临床特征差异无显著性。第1天DD基因型和ID 基因型ACE水平分别为33.42±7.93 U/L和31.53±7.56 U/L，显著高于II基因型的25.53±7.56 U/L（P<0.01）；第3天和第7天，三者ACE水平逐渐下降，但仍是DD高于ID，两者显著高于II。比较危重病评分，生后第1天 DD 基因型为87.37±8.30，低于ID基因型的95.82±5.85和II基因型95.88±6.85，差异有显著性，ID和II间差异无显著性；第3天，DD基因型显著低于ID基因型(92.95±7.10 vs 96.94±5.85，P<0.05)，与II无差异，ID和II间也无差异；第7天，三者间无差异。结论：ACE基因插入/缺失多态性与新生儿危重症有相关性，DD基因型携带者的病情相对重，血清ACE水平相对高，虽然疾病会对血清ACE水平有所影响，但决定ACE水平的根本因素是个体间基因型的差异。

OBJECTIVE: To 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. METHODS: ACE 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. RESULTS: Of 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). CONCLUSIONS: ACE 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.