A group of 33 schizophrenic patients were typed for HLA-SD antigens and their qualitative clinical responses to chlorpromazine therapy determined. A highly significant positive correlation was found between response to chlorpromazine and HLA-A1 positive, while HLA-A2 positive subjects showed a significant negative correlation to chlorpromazine treatment.
In a second group of 17 patients the clinical responses to chlorpromazine were evaluated quantitatively, by WPRS, in HLA-A1 positive and HLA-A1 negative patients. There were no pre-treatment differences in the scores. After treatment the scores of positive patients were significantly lower, indicating that they responded to a greater degree.
Since the frequency of HLA-A1 in hebephrenic patients is higher than that in other schizophrenics this may explain our earlier finding that hebephrenics, as a group, respond better to chlorpromazine than do other schizophrenics.