6-Pyruvoyltetrahydropterin Synthase Deficiency Two-Case Report
Suthipong Pangkanon MD*, Wiyada Charoensiriwatana MSc**, Sahas LiamsuwanMD***
Affiliation : * Genetic Unit, Department of Pediatrics, Queen Sirikit National Institute of Child Health ** Department of Medical Sciences, National Institute of Health, Nontaburi *** Pediatric Neurology Unit, Department of Pediatrics, Queen Sirikit National Institute of Child Health
6-Pyruvoyltetrahydropterin Synthase (PTPS) deficiency is the most common cause of hyperphenyla- laninemia due to tetrahydrobiopterin deficiency. The presenting symptoms of PTPS deficiency are mental retardation, convulsions, disturbance of tone and posture, drowsiness, irritability, abnormal movements, hypersalivation, and swallowing difficulties(1-3). The authors reported the first two cases of PTPS deficiency in Thailand. Both cases were male infants who showed phenylalanine levels of 25.23 mg/dl and 23.4 mg/dl respectively. The urinary pterins analysis showed low biopterin and high neopterin. The percentage of urinary biopterin was also found to be very low. The mutation analysis of the first case revealed a point mutation of exon 4, a homozygous C to T transition at nucleotide 200 in codon 67 (T67M), and the second case showed a compound heterozygous of exon 4, C to A transition at nucleotide 200, and exon 5, C to T transition at nucleotide 259 of the PTS gene confirming that they had PTPS deficiency. Treatment was started with neurotransmitters and a low phenylalanine diet. Family carriers were detected by means of urinary pterins determination and mutation analysis.
Keywords : Hyperphenylalaninemia, 6-Pyruvoyltetrahydropterin synthase, Tetrahydrobiopterin
