Experimental Gerontology 39 (2004) 629–635

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polymorphisms PON1 192 and 55 and longevity in Italian centenarians and Irish nonagenarians. A pooled analysis

a,* b b b c Irene M. Rea , Pascal P. McKeown , Dorothy McMaster , Ian S. Young , Chris Patterson , d b e e Maurice J. Savage , Christine Belton , Francesca Marchegiani , Fabiola Olivieri , f f Massimiliano Bonafe , Claudio Franceschi

aDepartment of Geriatric Medicine, Queens University of Belfast, Whilta Medical Building, 97 Lisburn Road, Belfast BT7 9AB bDepartment of Medicine, Queens University of Belfast, Belfast, United Kingdom cEpidemiology, Queens University of Belfast, Belfast, United Kingdom dChild Health, Queens University of Belfast, Belfast, United Kingdom eItalian National Research Centres on Aging, Ancona, Italy

Received 5 August 2003; received in revised form 8 October 2003; accepted 21 November 2003

Abstract

Background. PON1, an arylesterase, associated with high density lipoprotein (HDL), protects low density lipoprotein (LDL) against oxidative modification. Common polymorphisms PON1 55 (L/M) and 192 (Q/R) in the PON1 gene associate with atherosclerosis and heart disease. Because long-lived people seem protected from premature vascular death, we conducted a pooled statistical analysis to assess any association between these polymorphisms and longevity in a large combined group of Italian centenarians and octo/nonagenarians from

Materials and methods. Separated DNA was available from 1479 subjects from Italy and Northern Ireland (NI). In Italy 308 (males 67, females 241, mean age 100.8, SD2.1 years) and 579 young controls (males 347, females 232, mean age 40.7, SD 12.7 years) includedinthestudy.InNI,296octo/nonagenarians(males92,females204,meanage (mean age 13.0, SD 1.4 years) had available DNA. PON1 55 (L/M) and 192 (Q/R) polymorphisms were studied using a PCR-RFLP

(mean age 13.0, SD 1.4 years) had available DNA. PON1 55 (L/M) and 192 (Q/R) polymorphisms were studied using a PCR-RFLP approach. Results. There was a significant difference in PON1 192 genotypes in Italian centenarians compared to younger controls (X2 ¼ 6:8; df ¼ 2; p ¼ 0:03) and a similar but non significant trend between octo/nonagenarian and young subjects in NI (X2 ¼ 4:0; df ¼ 2; p ¼ 0:14). Using logistic regression analysis on the combined Italian and Irish datasets, there was a small survival advantage for centenarian and octo/nonagenarian subjects who were heterozygous for PON1 192 R allele, (OR 1.3, CI 1-1.6; p ¼ 0:04) with a stepwise increase for RR homozygous subjects (OR 1.7, CI 1.1-2.6; p ¼ 0:02), compared to QQ subjects. Comparing R and Q alleles there was a survival advantage for octo/nonagenarian/centenariansubjectswhocarriedtheRallele(OR1.3,CI1.1-1.5;p ¼ 0:007),buttherewasnosex-specificeffectðp ¼ 0:77Þ: LL, LM and MM genotypes of PON 55 polymorphisms showed similar frequencies in Italy (39.9, 47.0, 13.1%) and Ireland (39.5, 48.6, 11.9%) with no age or sex-related differences. The PON1 192R/Q and PON55L/M loci were in strong linkage disequilibrium with a Lewontin’s D0 coefficient 20.928 (elderly) and 20.965 (young). There was a significant difference in haplotype frequency of these linked loci in older compared to younger subjects (Likelihood Ratio X2 ¼ 9:60; df ¼ 3; p ¼ 0:02).

Conclusion. These data suggest a modest association between the 192R allele and longevity in two very elderly populations in two European countries. Being homozygous for 192 RR further enhances survival advantage but this effect was not found to be sex specific. This finding is of interest because the 192R allele has previously been associated with increased risk of coronary heart disease. On the other hand, the 192R allele shows higher enzymatic activity, using paraoxon as substrate, and we postulate that its role in the metabolism of potentially toxic chemicals or other metabolic pathways may be important in survival to very old age. q 2004 Elsevier Inc. All rights reserved.

Keywords: Allele; Polymorphisms; Genotype

* Corresponding author. Tel.: þ44-28-9027-2156; fax: E-mail address: i.rea@qub.ac.uk (I.M. Rea).

I.M. Rea et al. / Experimental Gerontology 39 (2004) 629–635

two large cohorts of very elderly subjects-centenarians in Italy and octo/nonagenarians from the Belfast Elderly Longitudinal Free-living Ageing STudy (BELFAST) in Northern Ireland.

1. Introduction

Population demographics are changing with an increas- ing proportion of the population living into old age. Understanding the processes involved in ageing is important in order to maximise the quality of life of elderly people. It is likely that factors which influence longevity and healthy ageing include both genetic and non- genetic factors. In the Western world, atherosclerotic- related diseases and cancer remain the major causes of morbidity and premature death.

2. Material and methods

2.1. Subjects and controls

Italy. A sample of 579 Italian unrelated young subjects (347 males and 232 females, mean age 40.7 years, SD12.7 years, age range 20–65 years) and a sample of 308 unrelated centenarians (241 females and 67 males) were analysed as described previously (Bonafe et al., 2002). The samples were recruited in both Northern Italy (368 young subjects and 216 centenarians) and Southern Italy (211 young subjects and 92 centenarians). Control subjects were apparently healthy at the time of blood collection judging from clinical examination and recent clinical history. All subjects gave informed consent.

The paraoxonases (PON 1, 2, 3), a group of enzymes which display arylesterase activity, are clustered on the long arm of chromosome 7. Paraoxonase 1 (PON1) which hydrolyses several substrates, including paraoxon, is associated with high density lipoprotein (HDL) where it protects LDL against oxidative modification in vitro (Mackness et al., 1993; Watson et al., 1995), thus implicating PON1 as an anti-atherogenic and anti-inflam- matory enzyme.