Subtle brain dysfunction in treated 6-pyruvoyl-tetrahydropterin synthase deficiency: relationship to motor tasks and neurophysiological tests

• Published in: Brain & development (Tokyo. 1979) 2004-03, Vol.26 (2), p.93-98
• Main Authors: Kao, Chuen-Der, Niu, Dau-Ming, Chen, Jen-Tse, Shan, Din-E., Lin, Yung-Yang, Wu, Zin-An, Liao, Kwong-Kum
• Format: Article
• Language: English
• Subjects: 6-Pyruvoyl-tetrahydropterin synthase; Acoustic Stimulation; Adolescent; Biopterins - biosynthesis; Biopterins - deficiency; Brain Diseases, Metabolic, Inborn - enzymology; Brain Diseases, Metabolic, Inborn - physiopathology; Brain Diseases, Metabolic, Inborn - psychology; Cerebral Cortex - enzymology; Cerebral Cortex - physiopathology; Child; Cortical excitability; Cues; Electric Stimulation; Electromagnetic Fields; Electrophysiology; Evoked Potentials, Somatosensory - physiology; Female; Humans; Magnetics; Male; Movement Disorders - enzymology; Movement Disorders - physiopathology; Movement Disorders - psychology; Movement rhythm variation; Phosphorus-Oxygen Lyases - deficiency; Reaction Time - physiology
• ISSN: 0387-7604; 1872-7131
• DOI: 10.1016/S0387-7604(03)00098-6

6-Pyruvoyl-tetrahydropterin synthase (6PTPS) deficiency is a major cause of biopterin deficiency. 6PTPS patients usually have an elevated serum phenylalanine level, a deficiency of neurotransmitters (serotonin and dopamine), and neurological symptoms, if without treatment. We herein investigated the possibility of neurological dysfunction in early-treated patients. In the study, 12 early-treated 6PTPS patients were studied. Their auditory simple reaction time, movement rhythm variation (MRV), somatosensory evoked potentials to median nerve stimulation, and hand muscle responses to transcranial magnetic stimulation, were measured. MRV is a test of repetitive voluntary movements, and was used with and without auditory cues at 0.3 Hz. The 6PTPS patients had an increased motor threshold but normal motor and sensory central conduction times. They performed very well in simple reactions (6PTPS 208.4±16.7 ms, control 200.3±11.7 ms, p=0.18), but not in continuous tasks. The continuous performance tests showed that MRV had increased in the 6PTPS patients (with cues: 6PTPS 7.35±0.94, control 5.47±0.80, p