n. a type of biological marker that is simpler to detect than genetic sequences and that may be useful in researching vulnerability to a wide range of psychological and neurological disorders. Endophenotypes may be a useful link between genetic sequences and their external emotional, cognitive, or behavioral manifestations. [coined in the 1970s by U.S. behavioral geneticist and clinical psychologist Irving I. Gottesman (1930– ) and British psychiatrist James Shields (d. 1978)]