Visibility of the nailfold plexus and heredity.

The parents of 37 normal healthy teenagers selected on the basis of nailfold capillary patterns (16 low-plexus children and 21 high-plexus children) were examined by capillary microscopy and rated "blindly" for plexus visualization scores (PVS). The hypothesis that high PVS is a hereditary trait transmitted as a monogenic autosomal dominant is supported by these data. The additional hypothesis that the high PVS may be associated with a higher social class is also confirmed in this sample. The transmission of high PVS in schizophrenics, where it is frequently observed in association with more serious features of this disease, appears to follow the same mode of inheritance as in normal subjects. The importance of detecting a biological hereditary characteristic which appears to have a modifying effect on the schizophrenic process is emphasized.