Extensive epidemiologic studies have suggested that adult disease risk is associated with adverse environmental conditions early in development. Although the mechanisms behind these relationships are unclear, an involvement of epigenetic dysregulation has been hypothesized. Here we show that individuals who were prenatally exposed to famine during the Dutch Hunger Winter in 1944 -45 had, 6 decades later, less DNA methylation of the imprinted IGF2 gene compared with their unexposed, same-sex siblings. The association was specific for periconceptional exposure, reinforcing that very early mammalian development is a crucial period for establishing and maintaining epigenetic marks. These data are the first to contribute empirical support for the hypothesis that early-life environmental conditions can cause epigenetic changes in humans that persist throughout life.developmental origins ͉ DNA methylation ͉ insulin-like growth factor II ͉ nutrition ͉ periconception S uperimposed on the DNA sequence is a layer of epigenetic information that is heritable, particularly during mitosis, and controls the potential of a genomic region to be transcribed (1). Methyl groups coupled to cytosines in cytosine-guanine (CpG) dinucleotides and modifications of histones that package the DNA are the two main molecular marks that compose this information and regulate chromatin structure and DNA accessibility (2).Animal studies have indicated that certain transient environmental influences can produce persistent changes in epigenetic marks that have life-long phenotypic consequences (3, 4). Early embryonic development is of special interest in this respect, because this is a crucial period for establishing and maintaining epigenetic marks (5). Indeed, culturing of preimplantation mice embryos found that epigenetic marks are susceptible to nutritional conditions in the very early stages of mammalian development (6, 7). One of the rare opportunities for studying the relevance of such findings to humans is presented by individuals who were prenatally exposed to famine during the Dutch Hunger Winter (8). This period of famine was the consequence of a Germanimposed food embargo in the western part of The Netherlands toward the end of World War II in the winter of 1944-45. During this period, registries and health care remained intact, so that individuals who were prenatally exposed to this famine can be traced. Moreover, the period of famine was clearly defined, and official food rations were documented. These unique features allow us to assess whether prenatal exposure to famine is associated with persistent epigenetic differences in humans.One of the best-characterized epigenetically regulated loci is insulin-like growth factor II (IGF2). IGF2 is a key factor in human growth and development and is maternally imprinted (9). Imprinting is maintained through the IGF2 differentially methylated region (DMR), the hypomethylation of which leads to bi-allelic expression of IGF2 (10). We recently studied IGF2 DMR methylation in 372 twins (11). IGF2 D...

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We conducted a sib pair study in very old subjects for the purpose of mapping longevity loci. In the present analysis, we explore whether our recruitment strategy has resulted in a population enriched for a heritable component for exceptional longevity. Our study includes families with at least two longliving siblings (men aged 89 years or above; women aged 91 years or above). Data were collected on date of birth and, if applicable, date of death of parents, brothers and sisters, offspring, and spouses of the long-living participants. Standardised mortality ratios (SMRs) compared with the general Dutch population, were calculated. The SMR for all siblings of the long-living participants was 0.66 (95% CI 0.60-0.73). A similar survival benefit was also observed in the parents (SMR ¼ 0.76, 95% CI 0.66 -0.87) and in the offspring of the long-living subjects (SMR ¼ 0.65, 95% CI 0.51-0.80). The SMR of the spouses of the long-living subjects was 0.95 (95% CI 0.82 -1.12). The familial clustering of extended survival is unlikely to be caused by ascertainment bias, because in all analyses the long-living participants were excluded. Moreover, it is also unlikely to be caused by environmental factors, because the spouses of the long-living participants had a mortality risk comparable with the general Dutch population, whereas they share the same environment. We conclude that our sample is genetically enriched for extreme survival.

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