Genetic and Environmental Influences on Premature Death in Adult Adoptees

TLDR

The study aimed to evaluate how genetic and environmental factors influence adult mortality by following 960 families of adoptees born 1924‑1926 who were placed with unrelated adoptive parents. Researchers assessed all‑cause and cause‑specific mortality risks between ages 16 and 58 for adoptees whose biological or adoptive parents died before age 50 or 70, comparing these risks to adoptees whose parents were alive at those ages. Adoptees whose biological parents died before age 50 had significantly higher risks of death from all causes (RR 1.71), natural causes (1.98), infections (5.81), and cardiovascular/cerebrovascular causes (4.52), whereas adoptees with deceased adoptive parents showed risks near unity except for cancers (RR 5.16); similar but weaker patterns emerged for deaths before age 70, indicating a strong genetic component for infections and vascular causes and an environmental influence for cancers. (N Engl J Med 1988; 318:727–32.).

Abstract

To assess genetic and environmental influences on adult mortality, we followed 960 families that included children born during the period 1924 through 1926 who were placed early in life with adoptive parents unrelated to them. We evaluated the risks of dying from all causes or from specific groups of causes between the ages of 16 and 58 years for adoptees with a biologic or adoptive parent who died of the same cause before the age of either 50 or 70. We compared these risks with the adoptees' risk of dying from the same causes between the ages of 16 and 58 when either the biologic or adoptive parents were still alive at the ages of 50 and 70. The death of a biologic parent before the age of 50 resulted in relative risks of death in the adoptees of 1.71 (95 percent confidence interval, 1.14 to 2.57) for all causes, 1.98 (1.25 to 3.12) for natural causes, 5.81 (2.47 to 13.7) for infections, 4.52 (1.32 to 15.4) for cardiovascular and cerebrovascular causes, and 1.19 (0.16 to 8.99) for cancers. The death of an adoptive parent resulted in relative risks of death in the adoptees that were close to unity for all causes, natural causes, and infections, 3.02 (0.72 to 12.8) for vascular causes, and 5.16 (1.20 to 22.2) for cancers. A similar but weaker pattern was observed when either a biologic or adoptive parent died before the age of 70. We conclude that premature death in adults has a strong genetic background — especially death due to infections and vascular causes. In contrast, death from cancer, and possibly also from vascular causes, appears to be influenced by the family environment. (N Engl J Med 1988; 318:727–32.)