Dermatoglyphic a-b ridge count as a possible marker for developmental disturbance in schizophrenia: replication in two samples.

The aim of this study was to conduct an epidemiological analysis of quantitative dermatoglyphic traits as a marker of prenatal disturbance during the second trimester of life in schizophrenic patients. TFRC (Total Finger Ridge Count) and TABRC (Total a-b Ridge Count) were studied in a sample of 38 schizophrenic patients and 69 healthy individuals. A significant decrease of the a-b ridge count was found in patients compared to controls, with a significant linear trend across the population distribution (OR linear trend = 1.6; 95% CI = 1.0-2.4), indicating that the effect was not confined to a subgroup of cases with values in the lowest range. This finding was replicated in a second, larger sample (OR linear trend = 1.3; 95% CI = 1.0-1.8). The suggestion that a-b ridge count is associated with genetic risk for schizophrenia needs to be investigated further. TFRC did not distinguish between patients and controls. The a-b ridge count may be a continuous risk factor for later schizophrenia, pointing towards a disturbance occurring during the second trimester of prenatal life, a period of critical CNS growth.