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Identification of three novel 6‐pyruvoyl‐tetrahydropterin synthase gene mutations (226C>T, IVS3+1G>A, 116‐119delTGTT) in Chinese hyperphenylalaninemia caused by tetrahydrobiopterin synthesis deficiency

The enzyme 6‐Pyruvoyl‐tetrahydropterin synthase (PTS) deficiency is the major cause of BH4‐deficient HPA. The frequency of BH4‐deficient HPA was estimated to be around 30% among Chinese HPA population in Taiwan, which is much higher than that in Caucasian population (1.5‐2% of HPA). Approximately 86% of Chinese BH4‐deficient HPA was found to be caused by PTS‐deficiency. Seven mutations – namely R25G, N52S, V56M, V70D, P87S, D96N, and T106M – had been identified in Chinese PTS‐deficient patients previously. In this study, five additional mutations in the PTS gene, namely 200C>T (T67M), 226C>T (L76F), IVS3+1G>A (K54X), 116‐119delTGTT (K38X) and 169‐171delGTG (V57del), were identified by PCR and DNA sequencing in Chinese PTS‐deficient patients. The 116‐119delTGTT introduces a frameshift stop after lysine of codon 38 (K38X). The G‐to‐A transition at the consensus sequence of splicing donor site of exon 3 (IVS3+1G>A) resulted in exon 3 skipping of the PTS transcript and caused a frameshift stop after lysine of codon 54 (K54X). The T67M and V57del mutations have been found in Caucasian PTS deficient patients, while the L76F, IVS3+1G>A, and K38X mutations are novel. None of 100 normal alleles screened was found to have the L76F substitution, which indicated that the L76F substitution is a mutation causing PTS deficiency. Hum Mutat 18:83, 2001. © 2001 Wiley‐Liss, Inc.