Participants (n = 9,219) of The Copenhagen City Heart Study were genotyped for the p53 Arg72Pro polymorphism8 using the Nanogen system.40 Taking advantage of the 100% complete follow- up, we were able to examine association between the Arg72Pro genotype and risk of any cancer8 (Fig. 3). For Arg/Pro heterozy- gotes versus Arg/Arg homozygotes we found a borderline increased gender and age adjusted hazard ratio for all cancer of 1.1 (95% CI: 1.0–1.2), but since the equivalent hazard ratio for Pro/Pro homozy- gotes was nominally decreased at 0.9 (0.8–1.1), we considered this as a chance-finding.

Several germline SNPs in TP53 have been most of 2 them located in introns and of uncertain significance. The SNP rs1042522 is, however, located in exon 4 and results in an Arginine to Proline amino acid substitution in position 72 of the p53 protein.

In 6 subtypes of cancer (gastrointestinal, respiratory, urologic, female, male and other types) including risk of melanoma and non-melanoma skin cancer (both in the “other” category), we gener- ally did not find any association with Arg72Pro genotype (Fig. 3); surprisingly however, the risk of hematologic cancer increased 2-fold in Arg/Pro heterozygotes vs. Arg/Arg homozygotes (p < 0.001), with a similar trend in Pro/Pro homozygotes. This 2-fold increased risk was

Arg72Pro Polymorphism of p53

Arg72Pro was first discovered in 1986 as a difference in phoretic mobility of two versions of p53.19 Since then, this SNP been implicated in risk of cancer, hepatitis C and schizophrenia, outcome for patients with traumatic brain injury, in placental and in ageing.20-27 There are marked functional differences

 Latitude, °100N-80N-60N-40N-20N-Equator-20S-  PeruJamaicaSouth Africa 40S-10T T T T20 30 40 50 60p53 Pro72 allele frequency, %70 

significant even after correction for multiple testing, and therefore might represent a real phenomenon rather than a chance finding; however, this needs to be confirmed in another independent study.

We next sought to validate earlier findings suggesting association of Arg72Pro with risk of a variety of other diseases.20-27 However, in our study Arg72Pro genotype was not associated with risk of cardiovascular or other diseases (Fig. 4, left).8

Arg72Pro and Mortality

. Having examined Arg72Pro genotype and E morbidity, we next examined morTtality.8 The overall 12-year survival after blood saUmpling was increased in Arg/Pro heterozygotes wBith 3% (p = 0.003) and in Pro/Pro homozygoteIs with 6% (p = 0.002) vs. R Arg/Arg homozygotes (Fig. 5, left). This corre- T sponds to a sex and age adjusted hazard ratio for S death from any cause in Arg/Pro heterozygotes and I Pro/Pro hoDmozygotes vs. Arg/Arg homozygotes of 0.88 (95% CI: 0.81–0.96) and 0.82 (0.68–0.97), T respectively (Fig. 4, right). This reduction in risk of O death translates into an increased median survival of N 2 years and 3 years for Arg/Pro heterozygotes and Pro/Pro homozygotes vs. Arg/Arg homozygotes (Fig. 5, right). In accordance with this, the frequency of Pro allele appeared to increase with increasing age age 90 years, when the mortality of the partici- begins to rise (Fig. 6). The Leiden 85-plus study found increased survival in Pro/Pro homozygotes Arg/Arg homozygotes among 1226 partici- 85 years or older followed for 5–10 years.26

tsuguA 61 90:80 ta ]1.512.161.901[ yb dedaolnwoD

Figure 2. p53 Pro72 allele frequency as a function geographical latitude. Controls from 46 case-control studies of cervical cancer and Arg72Pro genotype (n = 7625)22 were aggregated according to geographical region. Circle size denotes relative sample size.

. E C N E I C S O I B S E D N A L 8 0 0 2 ©

As already shown, the stepwise increased longevity in p53 Arg/Pro heterozygotes and Pro/Pro homozy- gotes vs. Arg/Arg homozygotes was not explained by decreased risk of developing cancer, cardiovascular disease or other life-threatening diseases (Fig. 4, right). More likely, it was explained by a better prognosis in Arg/Pro heterozygotes and Pro/Pro homozygotes vs. Arg/Arg homozygotes after the diagnosis of cancer or other life-threatening disease: the cumulative 5- year mortality after a cancer diagnosis was reduced in Arg/Pro heterozygotes and Pro/Pro homozygotes vs. Arg/Arg homozygotes by 9% (p = 0.003) and 13% (p = 0.03) (Fig. 7). The reduced 5-year mortality corresponds to a decreased age and sex adjusted hazard ratio for death after a diagnosis of cancer of 0.87 (95% CI: 0.77–0.98) in Arg/Pro heterozygotes and of 0.74 (0.56–0.98) in Pro/Pro homozygotes vs. Arg/Arg homozygotes (Fig. 4, right). Thus, mortality after a cancer diagnosis was stepwise reduced with increasing number of Pro72 alleles (trend-test, p = 0.005). Also for other diseases including diabetes, lung diseases and infections, mortality was reduced by 10% by each number of Pro72 alleles (trend-test, p = 0.002) (Fig. 4, right). Similarly, the risk of death after a cardiovascular diagnosis was nominally but

Figure 3. Risk of any cancer and cancer subgroups according to p53 Arg72Pro genotype in the general population.8 Participants were from the Copenhagen City Heart Study. Numbers of participants vary slightly because some participants were excluded due to development of disease prior to follow-up. The sum of events in the cancer subgroups do not add up to give the numbers of events in any cancer since only first cancer events were included.

 Participants/Events Mortality4934/1287 °eH:p53 Arg72Pro Overall 3623/840 ieArg/Arg 862/137 ie@Arg/Proe@Pro/ProParticipants/Events Morbidity :4933/1071 e 1072/592 @Cancer 3623/853 ies 853/426 eo662/124 -+___e—i-_4 124/56 -—e——4934/1548 e 1548/801 ¢Cardiovascular — 3622/1105 eH 1105/522 eH662/196 -——é— 196/93 -—e—H4933/3980 é gge0/1182 ;Other 3619/2807 He 2907/769 eH662/542 —— 542/124 ——e—THOT OTTO TH0.7 0.8 101.1 1.3 0.5 0.6 0.8 1.0 1.1Hazard ratio (95% confidence interval)