Association of insertion–deletion polymorphism of ACE gene and Alzheimer’s disease in Egyptian patients

Abstract

Introduction: Alzheimer’s disease (AD) is a progressive, neurodegenerative disease. Many studies proposed an association of the insertion (I)/deletion (D) polymorphism (indel) in intron 16 of the gene for angiotensin I-converting enzyme (ACE) on chromosome 17q23 with Alzheimer’s disease. ACE indel and related haplotypes associated with AD risk have reduced plasma ACE whereas protective genotypes have elevated ACE.
Object: To investigate whether there is a correlation between polymorphisms of the ACE I/D locus gene and AD in Egyptian patients and to determine whether there is a difference in ACE activity in the plasma of clinically diagnosed AD patients.
Methods: Subjects of this study are 84 dementia patients diagnosed as having Alzheimer’s disease, 45 males and 39 females aged 65 ± 7 years from the Geriatric Department at Ain-Shams University Hospitals and 86 individuals as non dementia controls, 44 males and 42 females aged 63 ± 6 years. All subjects were genotyped for the common insertion/deletion polymorphisms for ACE gene locus, and ACE plasma activity assay was measured for AD patients.
Results: There was statistically significant difference in the frequency of the ACE insertion/deletion alleles between the cases and controls where the I allele distribution in AD cases and controls was 74% vs. 15%, and the I/I genotype frequency was 60% vs. 5%, respectively. They both reached a statistical significance range (I allele frequency: OR =3.714, 95% CI 1.311–10.523, p< 0.01; I/I genotype frequency: OR = 3.18 95% CI 2.33–4.33, p< 0.01). But no significant difference in ACE plasma level was found between different genotypes in our AD patients.
Conclusions: Our present study supports the hypothesis of implication (I allele) of ACE gene polymorphism in the development of AD. On the other hand, we did not find significant difference in plasma ACE activities when compared with different studied genotypes.

Keywords: ACE I/D polymorphism; Alzheimer’s disease; Plasma ACE