Theory of the age dependence of mortality from congenital defects

A theory is presented, based on the evidence that the congenital defect of an individual is at one of many different-levels. It is supposed that the i ndividual mortality risk from congenital defect is lognormally or normally distributed in the population. The relationship between childhood mortality from seven congenital defects and age is described. It uses data from the US during the period 1979-1991. Mortality from five congenital defects is i nversely proportional to age. Mortality from two congenital defects is inve rsely proportional to the second power of age. The presented theory explain s these two observed types of mortality decline with age. Childhood mortali ty from some infectious diseases is also inversely proportional to age duri ng childhood in different populations. It follows from this theory that the death from these infectious diseases up the age of 10 years may be caused by a hidden congenital frailty. (C) 2001 Published by Elsevier Science Irel and Ltd.