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Analysis of Common Polymorphisms in Angiotensin-converting Enzyme and Apolipoprotein E Genes and Human Longevity in Colombia

A. Forero,a,e,* Jorge Pinzo´n,a,* Gonzalo H. Arboleda,a,b Juan J. Yunis,a,b a a,d a,c Claudia Alvarez, Nohra Catan˜o, and Humberto Arboleda

de Patolog´ıa, de Pediatr´ıa, Facultad de Medicina dDepartamento de Cuidado y Practica, Facultad de Enfermer´ıa, Universidad Nacional de Colombia, Bogota´, Colombia eApplied Molecular Genomics Group, Department of Molecular Genetics, Flanders Interuniversity Institute for Biotechnology,

Received for publication January 11, 2006; accepted April 7, 2006

Background. Genetic analysis of human longevity may be useful for the understanding of molecular mechanisms implicated in age-related diseases. The molecular genetics of hu- man longevity is largely unexplored in Latin American populations and other developing countries.

Methods. To explore the possibility of an association of common polymorphisms in two candidate genes and longevity in Colombia, we analyzed two polymorphisms in apolipoprotein E (APOE) and angiotensin-converting enzyme (ACE) genes in a sample of 538 Colombian subjects (18–106 years), using previoulsy validated PCR-based meth-

Results. We found a significant decrease in ACE DD genotype (24 vs. 16%) between young and old subject groups (mean age: 45 vs. 77 years) ( p 5 0.03). The ACE DD genotype and D allele decrease was significant only in women. There were no differences for APOE polymorphism between young and old subjects.

Conclusions. Our results are compatible with the expected age-related decrease of ACE DD genotype. Future studies examining functional single nucleotide polymorphisms (SNPs) in the ACE gene and its correlation with serum ACE activity in the older subjects and their younger relatives in this sample are warranted.   2006 IMSS. Published by Elsevier Inc.

Key Words: Longevity, Aging, Genetic polymorphisms, Colombia.

Introduction

pend on the genetic background and may interact with en- vironmental features (4,5); it is expected that for a complex phenotype such as human longevity, non-lineal effects of specific genetic variants can be found (2). Although life expectancy is also increasing in developing countries hav- ing profound effects on health and social dimensions (life expectancy in Colombia is |70 years, in comparison, in countries such as Mozambique, Africa and Japan, Asia, it is about 37 and 81 years, respectively) (6), the molecular genetics of human longevity is largely unexplored in Latin America and other developing regions.

Genetic explorations of human longevity may shed light on molecular factors associated with resistance to several com- mon age-related diseases (1,2). The heritability of human longevity is estimated at |20–30%, although it varies in different ethnic groups and levels of longevity (3). It has been postulated that the effects of specific candidate gene polymorphisms on different human phenotypes may de-

Address reprint requests to: Dr. Humberto Arboleda, Instituto de Gene´tica, Universidad Nacional de Colombia, Bogota´, Colombia; E-mail: harboledag@unal.edu.co

Because cardiovascular disease is one of the main causes of death worldwide, polymorphisms in genes involved in vascular dysfunction such as apolipoprotein E (APOE)

*These authors contributed equally to this work.

0188-4409/06 $–see front matter. Copyright  2006 IMSS. Published by Elsevier Inc. doi: 10.1016/j.arcmed.2006.04.001

and angiotensin-converting enzyme (ACE) have been pos- tulated as strong candidates for longevity in different stud- ies searching for age-related differences in the frequency of alleles and genotypes related to cardiovascular risk in Cau- casian and Asian populations (2,7).

(11). The study was approved by the institutional ethics committee.

Laboratory Procedures

Genomic DNA was extracted from peripheral blood using the salting out method as described (12). Two ml of DNA solution (100–200 ng) was used for each PCR amplification reaction in a 25 ml final volume using 20 pmol of each primer, 200 mM of dNTPs and 0.6–0.75 U of Taq polymer- ase (Promega, Madison, WI) in a PTC100 Thermal Cycler (MJ Research, Watertown, MA).

APOE gene is localized in chromosome 19q (4 kb), cod- ing for a mature protein of 299 aminoacids, which has a key role in lipid transport and neural repair and plasticity (8). Two common SNPs lead to changes in positions 112 (nt 3937 T/C) and 158 (nt 4075 C/T) of the protein and produce the three classic APOE haplotypes: E2 (Cys112/ Cys158), E3 (Cys112/Arg158) and E4 (Arg112/Arg158), which have clear functional and differential effects on cell function and risk for some neurodegenerative and cardio- vascular diseases (8,9). ACE gene is localized in chromo- some 17q (20.5 kb), coding for a mature protein of 1306 aminoacids, which has a key role in bioactive peptides deg- radation and cardiovascular and neuronal homeostasis (7). A common insertion/deletion (I/D, an Alu insertion) poly- morphism in intron 16 of the gene with varying population frequencies around the world (10) has been described. In addition, particular genotypes in the ACE gene have been correlated with serum levels of the enzyme and associated with vascular (DD for myocardial infarction) and neurolog- ical disorders (II for Alzheimer’s disease) (7,10).