Angiotensin-converting enzyme insertion/deletion gene polymorphism in Egyptian children with CAP: A case-control study Heba Abouzeid | Usama M. Alkholy | Mohammed A. Abdou | Saeed M. Morsy | Hind M. Abdelrahman | Ashraf M. Sherif| Nermin Abdalmonem | Mohammed E. Hamed | Mayy A.N. Allah | Salah Al Morshedy | Shaimaa S.A. Elashkar | Maha A. Noah | Mohamed S. Hegab | Nagwa E. Akeel | Mustafa I.A. Hashem | Heba H. Gawish | Lobna Abdel Fattah Published in: Pediatric Pulmonology. 2017;1–7. Background: Community-acquired pneumonia (CAP) is a major cause of childhood morbidity and mortality worldwide. The angiotensin-converting enzyme (ACE) gene is a potential candidate gene for CAP risk. Objectives: In this study, we aimed to investigate whether the ACE insertion/deletion (I/D) polymorphism (rs4340) could be a genetic marker for CAP susceptibility in Egyptian children, and we also measured the serum ACE level to assess its relation to such polymorphism. Methods: This was a prospective case-control study included 300 patients with CAP, and 300 age, gender, and ethnicity matched healthy controls. The ACE I/D polymorphism (rs4340) at intron 16 was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while the serum ACE levels were measured by ELISA. Results: Compared to the control subjects, the frequencies of the ACE DD genotype and D allele were over represented in patients with CAP (OR = 3.05; [95%CI: 2.14-4.35] for the DD genotype; P < 0.001) and (OR: 1.8; [95%CI: 1.42-2.29]; for the D allele; P < 0.01, respectively). Patients with the DD genotype had significantly higher mean serum ACE levels (45.6 ± 11.4 U/L) compared to those with ID genotype (36.5 ± 8.3 U/L) and II genotype (21.6 ± 5.7 U/L); P < 0.01, respectively. Conclusion: The ACE I/D polymorphism (rs4340) may contribute to the genetic susceptibility of CAP in Egyptian children. The ACE D allele and DD genotype were associated with higher serum ACE levels among studied CAP patients.