Since the 1960s, psychiatrists have been hunting for substances
made by the body that might accumulate in abnormally high levels
to produce the symptoms associated with schizophrenia. In
particular, there was a search for chemicals that might be
related to the hallucinogens phencyclidine (PCP) or lysergic
acid diethylamide (LSD), which could explain the emergence of
psychotic symptoms in schizophrenia. This "auto-intoxication"
hypothesis led investigators on a wild goose chase where
substances, including the "Pink Spot" and the "Frohman Factor",
were isolated from people with schizophrenia and implicated in
their illness, but these findings were later discredited. The
mysterious GRIN3A is a new version of the hunt for an intrinsic
mechanism that produces schizophrenia-like symptoms. GRIN3A is a
gene that codes for the GluN3A subunit of the N-methyl-D-
aspartate-type (NMDA) receptor, a target for the
neurotransmitter glutamate in the brain. Functional NMDA
receptors usually have two GluN1 subunits and two GluN2