Urine sepiapterin excretion as a new diagnostic marker for sepiapterin reductase deficiency

Sepiapterin reductase deficiency (SRD) causes depletion of biogenic amines in the brain, early onset motor disorder, and intellectual disability. The diagnosticmarker for this rare disease is increased sepiapterin and biopterin in CSF. Through a new analytic methodology we demonstrated accumulation of sepiapterin in urine of four SRD patients several times greater than that found in healthy controls and carriers, regardless of age or treatment. Our findings suggest a newinterpretation of current theories of peripheral pterinmetabolismand provide a newnoninvasive diagnostic tool for children with early onset cryptogenetic developmental delay and/or movement disorder.