Gene/longevity association studies at four autosomal loci (REN, THO, PARP, SOD2)

1 2 1 1,3 1 1 G De Benedictis , L Carotenuto , G Carrieri , M De Luca , E Falcone , G Rose , S 3 3 3 4 5 6 7 Cavalcanti , F Corsonello , E Feraco , G Baggio , S Bertolini , D Mari , R Mattace , AI 8,9 10 3,10 Yashin , M Bonafe` and C Franceschi

Biology Department, University of Calabria of Electronics, Information and Systems Sciences, University of National Research Center on Aging (INRCA), Ancona and Cosenza

2Department of Electronics, Information and Systems Sciences, University of Calabria 3Italian National Research Center on Aging (INRCA), Ancona and Cosenza 4Chair of Geriatrics, University of Sassari 5Atherosclerosis Prevention Center, Internal Medicine Department, University of 6Institute of Internal Medicine, IRCCS Maggiore Hospital, University of Milano 7Chair of Geriatrics, University of Catanzaro, Italy 8Max Planck Institute for Demographic Research, Rostock, Germany 9Duke University, Centre for Demographic Studies, USA 10Department of Biomedical Sciences, University of Modena, Italy

The possibility that four loci (REN, THO, PARP, SOD2) are associated with longevity was explored by comparing the genotypic pools of subjects older than 100 years with those of younger subjects matched for sex and geographic area (northern and southern Italy). The markers (all located within the respective gene) were HUMREN4; HUMTHO1; HUMPARP ; SOD2(C/ (gt)845nt T) . In order to reduce the number of genotypes, multiallelic polymorphisms 401nt were recoded as diallelic according to allele size and frequency patterns (small: S, and large: L, alleles). A significant loss of LL homozygous genotypes was found at the THO locus in male but not in female centenarians with respect to matched controls. On the other hand no significant difference was found between case/control genotypic frequencies at REN, PARP, SOD2 loci. The latter loci therefore do not affect inter-individual variability in life expectancy (at least in terms of qualitative variants associated with the tested markers). However, the data is consistent with an association between the THO locus and longevity.

Keywords: human longevity; REN; THO; PARP; SOD2

Introduction

altering the risk of death at various ages.2 One approach to identifying some of these genes is a comparative analysis at candidate loci between gene pools of extremely elderly individuals and younger people from the same population.3 However, in this approach, special attention must be paid to case/control matching. This is particularly important when studies on Italian people are carried out, not only because different genetic components are present in the Italian gene pool,4 but also because migrations from southern

The number of genes which could affect inter-individ- ual variability in human life-span is expected to be high1 and probably the majority affect longevity by

Correspondence: G De Benedictis, Department of Cell Biology, University of Calabria, Arcavacata. 87030 Rende. Italy. Fax: + 39 984 49 29 11; Email: g.debenedictis@unical.it Received 4 December 1997; revised 11 March 1998; accepted 15 April 1998

matrix.21 Here SOD2 rapidly converts superoxide radicals into H O which is further detoxified by 2 2 catalase and glutathione peroxidase. A structural t to c substitution in the mitochondrial targeting domain has recently been described22,23 which changes valine to 16 alanine thus modulating the efficiency of mitochon- 16 drial transport.23

to northern Italy due to social and economic factors occurred in the last century. We have therefore planned a research project in which polymorphic markers at candidate loci were compared between centenarians and younger people, whose ancestry in the specific geographic area was checked back as far as the

Four autosomal genes, which code for proteins involved in fundamental metabolic pathways, were chosen as candidate loci. The genes were renin (REN), tyrosine hydroxylase (THO), poly(ADP-ribose) poly- merase (PARP) and superexidodismutase 2 (SOD2).

Materials and Methods

Both centenarians and controls were clinically healthy unre- lated subjects from various socio-economic backgrounds. Birth and residence of each individual in the specific geographic area (northern or southern Italy) was checked back as far as the grandparents' generation. All individuals gave informed consent prior to their inclusion in the study.

The REN gene (9 exons; 1q32 chromosome) codes for renin, an aspartylprotease which catalyses the first step of the biosynthetic cascade leading to angiotensin II. An (acag)n repeat polymorphic region5 lies in intron 7 (HUMREN4 marker). The five known alleles, desig- nated from 8 to 12 according to the repeat number (allele 9 is absent in Caucasians), show bimodal frequency distribution, with peaks at 8 and 11 repeats.6

Centenarians Only individuals who were over 100 years old on the day the blood was taken were included in the study. The oldest subject was a 109-year-old woman; 109 subjects (83 females and 26 males) were from northern Italy (Lombardia, Veneto, Liguria, Emilia-Romagna) and 87 subjects (60 females and 27 males) were from southern Italy (Sicilia, Calabria, Campania, Puglia).