Case report of a patient with schizophrenia and a mutation in the insulin receptor substrate-4 gene.

: This report deals with a female patient with schizophrenia who was found to have a mutation in the insulin receptor substrate-4 gene that is located on chromosome Xq22.3. Since this mutation is expected to change amino acid coding from histidine to tyrosine and cause an altered insulin receptor substrate-4 protein, and the insulin receptor substrate-4 protein may be involved in neuronal growth and function in the brain, it is possible that it is this insulin receptor substrate-4 gene mutation that underlies this patient's schizophrenia development.