Malignant Syndrome of Two Parkinson Patients due to Withdrawal of Drugs

Abstract

Background: A novel therapeutic strategy for phenylketonuria (PKU) has been initiated in Japan. Hyperphenylalaninemia (HPA) results from a phenylalanine hydroxylase (PAH) enzyme deficiency or a deficiency of its cofactor, tetrahydrobiopterin (BH 4 ). BH 4 can normalize blood phenylalanine levels in BH 4 deficiency, but typically not in PKU. However, since 1999 it has been reported that many HPA patients (serum phenylalanine <20 mg/dL) showed a gradual decrease of serum phenylalanine levels after 24 hours from BH 4 loading. The BH 4 responsiveness seems to be regulated in mild PKU by PAH mutations, and affected by the BH 4 dose and administration period. Methods and Results: In 2002 we formulated a provisional diagnostic criteria for patients with BH 4 -responsive PAH deficiency, and newly diagnosed 19 patients in 100 HPA cases between 2002 and 2006. The incidence in the recent 5 years for BH 4 -responsive mild PKU among patients with PAH deficiency was 25 %. Conclusion: A total of 31 patients was detected in the past 10 years, and the incidence detected using the provisional diagnostic criteria had increased to 25% among PAH deficient patients. BH 4 treatment for BH 4 -responsive mild PKU is a new and effective pharmacotherapy, which replaces or liberalises the phenylalanine-restricted diets for a considerable number of mild PKU patients. Ann Acad Med Singapore 2008;37(Suppl 3):77-8