Genetic Variation in the CYP2C Monooxygenase Enzyme Subfamily Shows No Association With Longevity in a

Friederike Flachsbart,1 Mike Ufer,2,3 Rabea Kleindorp,1 Susanna Nikolaus,4,5 Stefan Schreiber,1,4 and Almut Nebel1

1Institute of Clinical Molecular Biology, Christian-Albrechts-University Kiel, Germany. of Experimental and Clinical Pharmacology, University Hospital Schleswig-Holstein, Kiel, 3Novartis Pharma AG, Novartis Institutes for Biomedical Research, Basel, Switzerland. 4Clinic for Internal Medicine I, University Hospital Schleswig-Holstein, Kiel, Germany. 5Popgen Biobank, Christian-Albrechts-University, Kiel, Germany.

Address correspondence to Almut Nebel, PhD, Institute of Clinical Molecular Biology, Christian-Albrechts-University Kiel, Schittenhelmstraße 12, 24105 Kiel, Germany. Email: a.nebel@mucosa.de

and are regarded as susceptibility factors for age-related diseases. Furthermore, the CYP2C-encoding genes are known to be highly polymorphic, with a number of variants leading to changes in enzyme activity. These observations prompted us to investigate whether allelic variation in the CYP2C-encoding genes was associated with human longevity. In a compre- hensive haplotype tagging approach, we genotyped 56 single nucleotide polymorphisms located in the CYP2C gene family (CYP2C8, CYP2C9, CYP2C18, and CYP2C19) in our extensive collection of 1,384 long-lived individuals (cente- narians and nonagenarians) and 945 younger controls. None of the tested single nucleotide polymorphisms showed a significant association with the longevity phenotype at the allele, genotype, or haplotype level. These results suggest that there is no notable influence of sequence variation in the CYP2C genes on longevity in the examined German population.

Key Words: Genetic association—Centenarians—Ageing—Cytochrome P450—CYP2C enzymes.

Received May 16, 2011; Accepted June 14, 2011

Decision Editor: Placido Navas, PhD

the leading cause of death worldwide (12–14). Furthermore, CYP enzymes, particularly the CYP2C isoenzyme subfam- ily, are involved in the generation of reactive oxygen species (ROS) (15). Already more than 50 years ago, the accumula- tion of ROS was suggested to cause changes in physical or cognitive functions with ageing (16). To date, findings in the area of longevity research support a role of ROS and oxidative damage in age-related cellular decline ((17) and reviewed in (18)) and the development of age-related diseases (19).

rial trait to which various genetic and environmental factors are likely to contribute. About 30% of the varia- tion in adult life span is attributable to genetic parameters that show their strongest effect later in life (>60 years of age) (1–6). Epidemiological studies have revealed that people who survive to an exceptional old age (ie, ≥95 years) have often avoided or survived age-associated dis- eases. Hence, these long-lived individuals (LLI) show a favorable course of the ageing process and offer the unique opportunity to explore the genetic basis of the “healthy ageing” phenotype (7,8). It has been suggested that the genetic composition of the LLI differs from that of average-lived individuals in the following regards: (i) LLI are enriched for advantageous variants in so-called “longevity-enabling genes” and/or (ii) their genetic con- stitution shows a depletion of risk alleles for age-related diseases (9,10).

In humans, the CYP2 enzyme subfamily C consists of four genes (CYP2C8, CYP2C9, CYP2C18, and CYP2C19) that are located next to each other on chromosome 10q (Figure 1). These enzymes are mainly expressed in human liver (20) but are also expressed in various other tissues, including the cardiovascular system, where they are in- volved in the modulation of vascular homeostasis by me- tabolizing endogenous regulators of vascular tone (21). Consequently, CYP2C inhibition has been reported to reduce ischemia–reperfusion injury in myocardial tissue (22– 24). Furthermore, the CYP2C-encoding genes are also known to be highly polymorphic. Some of these variants

Cytochrome P450 enzymes (CYPs) are monooxygenases that are commonly known as important drug-metabolizing enzymes (11). They are also regarded as susceptibility fac- tors for age-related cardiovascular diseases that represent

2107Ne RE LN VLRINALREN ED SEINE PEUIVELALEN EARAINAI EV EE 96800k96700k96600k96500kCYP2Cc9CYP2C18CYP2C8CYP2C193                srocsstsssvortats:seseanotsoceasorssceveestis |coocesossecreastisseuorestss

Figure 1. CYP2C gene region on chromosome 10. The physical position (in kilobases) of all 56 genotyped single nucleotide polymorphisms refers to the Genome Reference Consortium Human genome build 37. A schematic representation of the gene structures for CYP2C18, CYP2C19, CYP2C9, and CYP2C8 is shown. The linkage disequilibrium (LD) plot of the locus is based on the measure r2 and was generated with Haploview 3.32 using the data of the whole German case–control sample.

1,384 LLI (centenarians and nonagenarians) and 945 appropriately matched younger controls.

lead to a markedly reduced or no enzyme activity, whereas other alleles induce an increased activity or ex- pression. In the context of drug metabolism, the variants CYP2C9*2 (rs1799853) and 2C9*3 (rs1057910) associ- ated with reduced enzyme activity are both known to be of particular clinical relevance. Recently, the U.S. federal drug agency (Food and Drug Administration) has encouraged prospective CYP2C9 genotyping as a clinical tool to allow for individualized dose adjustment of the oral anticoagulant warfarin that is metabolized by CYP2C9 (25).

Methods

Participants