Heritability of life span in the old order Amish

Although a familial contribution to human longevity is recognized, the natu re of this contribution is largely unknown. We have examined the familial c ontribution to life span in the Old Order Amish (OOA) population of Lancast er County, Pennsylvania. Analyses were conducted on 1,655 individuals, repr esenting all those born prior to 1890 and appearing in the mos. widely avai lable genealogy, surviving until at least age 30 years, and with known date of death. Mean age at death (+/-SD) in this population was 70.7 +/- 15.6 y ears, and this did not change appreciably over time. Parental and offspring ages at death were significantly correlated, as were ages of death among s iblings. Offspring longevity was correlated with longevity of both parents, and in more or less additive fashion. For example, mean offspring age at d eath was 69.4 +/- 15.3 years in individuals for whom both parents died befo re the age of 75 years (n = 280) and increased to 73.5 +/- 16.0 years in in dividuals for whom neither parent died before the age of 75 years (n = 311) . These differences were highly significant (P = 0.006). We estimated herit ability of life span to be 25% +/- 5%, suggesting that the additive effects of genes account for one quarter of the total variability in life span in the OOA. We conclude that longevity is moderately heritable in the OOA, tha t the genetic effects are additive, and that genetic influences on longevit y are likely to be expressed across a broad range of ages. Published 2001 W iley-Liss, Inc.