An update of the zinc deficiency theory of schizophrenia. Identification of the sex determining system as the site of action of reproductive zinc deficiency.

The following article updates the GZD theory of schizophrenia (1) by showing that male transmission of risk, the parental age effect, racial differences in birth seasonality, the disturbed sex ratios in the offspring of schizophrenic mothers and the association between diabetes and schizophrenia are explained by changes to zinc homeostasis. A genetic component to the disorder is now seen as unnecessary, transmission of risk by either parent, and twin concordance differences can be explained by other means. The primary site of action of GZD is identified as the putative ZFY sex determining system. Evidence suggesting that other mental disorders might be caused by GZD is also discussed.