An
assay for a GCH1
allele and associated
genotype for the screening, prediction, diagnosis, prognosis, treatment and
treatment response of psychiatric, neuropsychiatric, and neurological disorders, such as
schizophrenia,
schizoaffective disorder and bipolar disorder, and for defining treatments of such disorders. The presence of a variant in the GCH1
gene, alone or in conjunction with a measurement of low or altered
biopterin, or altered BH4
system measures, is used to screen for or diagnose subjects at high risk for developing a psychiatric, neuropsychiatric, or neurological disorders. The
assay of the GCH1
genotype, with or without
biopterin or a BH4 or BH4
system assay, may also be used to determine
antipsychotic or
mood stabilizer medication, as well as other treatments. For subjects with an impaired BH4
system, treatments to increase or normalize
biopterin, BH4, or the BH4 system can also be used, such as BH4 supplementation,
lithium treatment,
phenylalanine treatment, or other treatments and therapies.