Association Analysis of the SHC1 Gene Locus with Longevity in the Japanese Population

Received: 18 June 2003 / Accepted: 12 August 2003 / Published online: 2 October 2003 : Springer-Verlag 2003

Hidehiko Kamei and Toshio Kojima received their D.D.S. degree and are presently a Team Leader from the School of Dentistry, Aichi-gakuin University, Japan. Hidehiko Kamei is presently a trainee of the Human Genome Research Group at RIKEN and a graduate student of the Department of Periodontology, School of Dentistry, Aichi-gakuin University. His research interests include genetic analyses of centenarians and human diseases. He is also interested in comparative genomics, especially focusing on primates. Toshio Kojima's research interests include the relationship between genetic polymorphisms and human aging and also genetic risk factors of periodontal disease.

Abstract 

The SHC1 gene encodes a signaling and transforming protein that has been implicated in the aging process in worms and mammals. In this study, we examined 230 Japanese centenarians and 180 healthy younger controls and looked at the SHC1 locus as a candidate region that may be associated with longevity. We identified 12 single nucleotide polymorphisms (SNPs) within a 10-kb region encompassing the entire SHC1 gene from the DNA of 30 centenarians and 24 healthy younger controls. Five SNPs, including three nonsynonymous sites, lay within coding elements, six were located within introns, and one was in the 3' untranslated region. All of these SNPs were relatively rare, with a minor allele frequency of less than 5% in our subjects. A pairwise linkage disequilibrium analysis using the r2 statistic showed that two of the SNP pairs are in tight linkage disequilibrium at this locus. We investigated the possible association of SHC1 with longevity using association analyses with allelotypes and haplotypes but found that the SNPs identified in SHC1 had no impact on longevity for Japanese centenarians.

Materials and Methods 

Subjects 

A total of 230 Japanese centenarians (168 women, 62 men, age 100.81.5 years) living in the Tokyo metropolitan area were recruited between April 1999 and January 2001 for the second of the Tokyo Centenarian Study. Participants were identified from the national registry of centenarians, published by the Ministry of Health, Welfare, and Labor [11]. Among those enrolled, 162 were living at home, and 68 were institutionalized. None was in a care setting, and none was receiving tube feeding. The study included physical examination, measurement of body weight, height, electrocardiography, and blood pressure. Information regarding habitual food intake, alcohol and smoking habits, physical and cognitive functioning, use of medication, and past medical history was also collected [11]. Seven centenarians (20.4%) were receiving antihypertensive treatment, and ten had a history of treatment for cancer (two cancer, two colon, two prostate, one bladder, two breast, and one cancer of the uterus). Using the Mini-Mental State Examination (MMSE) and clinical dementia rating criteria, 170 (73.9%) were found to have varying degrees of cognitive impairment; this rate is similar to that of a previous study in Japan.

The regionally matched control subjects comprised 180 volunteers (116 women, 64 men, mean age 36.111.3 years) who were recruited from hospital and institutional medical and nursing school students, and bank clerks. The subjects were free from diseases such as coronary artery stroke, diabetes, and cancer. Smoking and alcohol consumption were moderate to nil. All subjects enrolled in this study were nonfasting. Venous blood (20 ml) was collected from all, and genomic DNA was prepared from peripheral blood according to standard protocols. Written informed consent was obtained from all participants directly or by proxy. This study was approved by the ethics committees of the Medical School of Keio University and of the RIKEN Yokohama Institute.

Introduction 

The influence of genes on aging and life expectancy is well established in species ranging from yeast to mammals. The SHC1 gene was originally described as a proto-oncogene, encoding three different isoforms of SHC1 proteins with molecular masses of 46, 52, and 66 kDa, respectively [1]. Recently, an unexpected correlation between life span and control of the oxidative stress response was reported. Targeted mutation of the SHC1 gene locus caused ablation of a splice variant of relative molecular mass 66,000 (p66shc) and resulted in selective resistance to oxidative stress and an extended life span in the mouse [2]. On a high-fat diet, the pBy D/(ppqq) where q and q are the frequencies of the 12 other alleles at loci A and B, respectively. Haplotype frequencies for multiple loci were estimated by the expectation-maximization method. Computations were performed using the SNPAlyze software (Dynacom, Mobara, Japan). Fig. 1 shows the SNP map of the genomic region containing SHC1, with open rectangles representing exons and horizontal lines representing introns. SNPs are indicated above the lines according to number. Transitions were more prevalent (9/10) than transversion substitutions (1/10). Only one insertion/deletion polymorphism was detected in SHC1. All SNPs were submitted to the dbSNP database in NCBI, with accession numbers listed in Table 2.

Results

Allele and genotype frequency distributions in young persons and centenarians