Application of a gas chromatography mass spectrometry computer system for clinical diagnosis.

Currently, one of the major clinical problems is diagnosis of inherited metabolic disorders in neonates which are caused by a defect of specific enzymes. In order to diagnose such diseases at an earlier stage, we have developed a new mass screening method, consisting of a gas chromatography mass spectrometry computer system with a newly developed 'Diagnosis Computer Program'. In this program, the chromatographic pattern of the urine of a patient with an inherited metabolic disorder is compared with that of a normal person. Internal standards are applied to simplify the comparison. The total ion current chromatogram is drawn with the relative retention times plotted on the horizontal axis and the relative intensities on the vertical axis. Diseases are diagnosed by characteristics and quantity of abnormal compounds in the urine. Reference to the stored mass spectra of abnormal compounds by a library search enables the diagnosis to be more precise. Using this program, twenty-six inherited metabolic disorders are routinely diagnosed. The diagnosis of tyrosinosis is used here as an example.