Platelet monoamine oxidase in families of chronic schizophrenics.

Many reports have described low platelet monoamine oxidase (MAO) activity in chronic schizophrenia. In an effort to determine whether this low activity is genetically controlled, the authors studied platelet MAO activity in the first-degree relatives of 12 chronic schizophrenics (who themselves had low platelet MAO activity). The 29 relatives had significantly lower mean Vmax and Km values than a control group. The authors postulate that the low platelet MAO activity among chronic schizophrenics may be a genetic marker for vulnerability to chronic schizophrenia.