Relevance of sequential development of dermatoglyphics to schizophrenia.

Since the embryogeneses of epidermal ridges of hands and feet are reported to be identical, although those of the feet develop two or three weeks later, a tendency for symmetry or correspondence between each side finger and toe pairs could be envisaged. Any prenatal insult could disturb such developmental mechanisms, causing the lowering of either finger or toe ridge counts which might result in augmentation of differences between them. To test this hypothesis, the differences between each side thumb and big toe ridge counts of 89 schizophrenic patients and 65 control subjects were assessed. These samples were also subgrouped into those with and without identical pattern distributions on each side of their thumb and big toe pairs. Female schizophrenics who displayed identical patterns manifested significantly greater differences between their right thumb and big toe ridge counts in comparison to the control subjects (P = 0.0142). To elucidate the contributory digit for such a greater difference, the ridge counts of the right thumbs and big toes of the female patients were compared with the corresponding counts of the control subjects. The mean ridge count of the big toes was lesser in the patient group compared with that in the control subjects, a difference, however, that did not attain statistical significance.