Genetic Studies of Quantitative Variation in a Component of Human Saliva.

For many years individual genetically controlled variation in the content of ABH and Lewis substance in human saliva has been recognized (Schiff & Sasaki, 1932; Grubb, 1948). A number of recent studies have suggested considerable variability in other constituents of human saliva. Thus, Kostlin & Rauch (1957), from the results of paper electrophoresis on human parotid and submandibular secretions, concluded that ‘the protein fractions of similar glands differ from one subject to the next ’. Immuno-electrophoresis of saliva has been carried out by Gab1 & Pastner (1960), who found a component with mobility similar to serum albumin whose concentration varied in the ten individuals studied. Patton & Pigman (1959) found, by Tiselius electrophoresis and ultracentrifugation, that the number of components obtained from parotid and submaxillary saliva showed more constancy in successive samples from the same individual than for samples from different individuals. However, with the exception of the ABH and Lewis secretion systems, little is known concerning the role of genetic factors in this variability. Furthermore, the only work on experimental animals appears to be that of Schneyer (1968), who has reported data suggesting genetic control of salivary amylase levels in mice. The present studies were undertaken on the premise that suitable techniques would demonstrate further variability in human saliva, and that genetic factors might be of importance in this variability. In this paper we will describe a specific component of saliva, detected by serological methods, which shows wide variation between individuals in its concentration. It will be referred to as SC,, indicating the salivary component migrating most anodally on electrophoresis. A quantitative immunodiffusion technique, a modification of methods described by Crowle (1961) and Hayward & Augustine (1957), has been applied to a series of salivas from twins and from family members in an attempt to determine whether the level of this factor is under genetic control.