Smooth pursuit ocular motor dysfunction in schizophrenia: evidence for a major gene.
OBJECTIVE
Evidence suggests that poor eye tracking relates to genetically transmitted vulnerability for schizophrenia. The authors tested competing models for the genetic transmission of poor eye tracking in a search for major gene effects.


METHODS
Samples from three studies (conducted in Minneapolis, New York, and Vancouver, B.C.) were pooled. Probands (N = 92) were diagnosed as schizophrenic by DSM-III criteria. Of the comparison subjects (N = 171), Vancouver patients were an epidemiologic first-episode group; at other sites unselected admitted patients were studied. First-degree relatives (N = 146) of 65 probands were also studied. Eye tracking was measured while subjects followed a horizontally moving, sinusoidally driven (0.4 Hz) spot of light on a screen. Performance was quantified by root mean square error. Data analysis was by complex segregation analysis (Bonney's class D regressive models).


RESULTS
A single major gene is needed to account for poor eye tracking in schizophrenic patients and their relatives. This gene alone can explain about two-thirds of the variance in eye tracking performance. A single gene alone (regardless of dominance) will, however, not account for the data; polygenic factors are also required.


CONCLUSIONS
Results support postulation of a single gene for ocular motor dysfunction, which may be a risk factor for schizophrenia. Eye tracking may be useful as a gene carrier test in genetic studies of schizophrenia.
Grove
W M
WM
Department of Psychology, University of Minnesota, MN 55455.
Clementz
B A
BA
Iacono
W G
WG
Katsanis
J
J
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D005190:Family; D005260:Female; D005819:Genetic Markers; D006801:Humans; D008297:Male; D008957:Models, Genetic; D011698:Pursuit, Smooth / Q000235:genetics*; D012559:Schizophrenia / Q000235:genetics* / Q000503:physiopathology; D012737:Sex Factors
D005819:Genetic Markers