MOST of the conditions to be considered in this symposium share one feature: their genetic origin. It could be profitable then to outline some of the principles of gene action and of the characteristics of genetic disease which will apply equally to all of the disorders to be reviewed.
To begin, a definition of gene action is offered. This must be an empirical one since it is not known, with any precision, what a gene is. However, it is known that the genetic material provides the most basic mechanism for homeostasis, ensuring that offspring will exhibit the characteristics of the parent, whether the offspring be daughter cells or human beings. This is accomplished by means of control over the formation and design of the vital molecules of the organism; those molecules which in their turn control its intricate and interrealted metabolic functions. It is for the most part these metabolic functions which we attempt to measure in the elucidation of gene action in disease, and it will be seen in the ensuing discussions that only rarely is one able to make any direct assessment of the physicochemical properties of these molecules which bear a specific relationship to the gene.
Much more commonly, a measurement is made of some form of activity of such substances, and a stepwise elucidation may be accomplished of the secondary effects which are consequent upon alterations in reaction rates or reaction failure. It is, in general, these secondary, tertiary, or consequential effects which are most easily measured, and which are the overt expressions of the disease. The principle illustrated here is, what a gene is said to do, depends upon which function we measure.
- Copyright © 1958 by the American Academy of Pediatrics