System and method for diagnosis and treatment of neuropsychiatric disorders

Abstract

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 or diagnose subjects at risk for developing a psychiatric, neuropsychiatric, or neurological disorder. The genetic assay, with or without a biopterin or BH4 system assay, may also be used to determine treatment regimens. 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.

What is claimed is: 
     
         1 . A method of treating a human subject for neuropsychiatric disorder, comprising the steps of:
 determining a GTP cyclohydrolase I (GCH1) −959 nt G/A genotype of the subject;   determining the levels of at least one of total biopterins, BH4, and dihydrobiopterin of the subject; and   treating the human subject for the neuropsychiatric disorder based on the genotype or biopterin level by administering a therapeutic amount of a BH4 supplement if the levels of at least one of total biopterins, BH4, and dihydrobiopterin of the human subject are below a predetermined threshold and if the human subject has an A allele of the GCH1 −959nt G/A genotype.   
     
     
         2 . The method of  claim 1 , wherein the neuropsychiatric disorder is cognitive impairment. 
     
     
         3 . The method of  claim 2 , wherein the BH4 supplement is sapropterin dihydrochloride. 
     
     
         4 . A method of treating a human subject for a neuropsychiatric disorder comprising the step of administering a therapeutic amount of a BH4 supplement. 
     
     
         5 . The method of  claim 4 , wherein the neuropsychiatric disorder is cognitive impairment. 
     
     
         6 . The method of  claim 5 , wherein the BH4 supplement is sapropterin dihydrochloride.