Metabolism and Genetics Group, Faculty of Pharmacy, iMed.UL-Research Institute for Medicines and Pharmaceutical Sciences,University of Lisbon, Portugal.
Mol Genet Metab. 2011;104 Suppl:S86-92. doi: 10.1016/j.ymgme.2011.07.026. Epub 2011 Jul 31.
Hyperphenylalaninemia (HPA, OMIM #261600), which includes phenylketonuria (PKU), is caused by mutations in the gene encoding phenylalanine hydroxylase (PAH), being already described more than 600 different mutations. Genotype-phenotype correlation is a useful tool to predict the metabolic phenotype, to establish the better tailored diet and, more recently, to assess the potential responsiveness to BH(4) therapy, a current theme on PKU field. The aim of this study was the molecular analysis of the PAH gene, evaluation of genotype-phenotype relationships and prediction of BH(4)-responsiveness in the HPA population living in South Portugal. We performed the molecular characterization of 83 HPA patients using genomic DNA extracted from peripheral blood samples or Guthrie cards. PAH mutations were scanned by PCR amplification of exons and related intronic boundaries, followed by direct sequence analysis. Intragenic polymorphisms were determined by PCR-RFLP analysis. The results allowed the full characterization of 67 patients. The mutational spectrum encompasses 34 distinct mutations, being the most frequent IVS10nt-11G>A (14.6%), V388M (10.8%), R261Q (8.2%) and R270K (7.6%), which account for 46% of all mutant alleles. Moreover, 12 different haplotypes were identified and most mutations were associated with a single one. Notably, more than half of the 34 mutations belong to the group of more than 70 mutations already identified in BH(4)-responsive patients, according to BIOPKU database. Fifty one different genotypic combinations were found, most of them in single patients and involving a BH(4)-responsive mutation. In conclusion, a significant number (30-35%) of South Portugal PKU patients may potentially benefit from BH(4) therapy which, combined with a less strict diet, or eventually in special cases as monotherapy, may contribute to reduce nutritional deficiencies and minimize neurological and psychological dysfunctions.
高苯丙氨酸血症（HPA，OMIM #261600），包括苯丙酮尿症（PKU），是由苯丙氨酸羟化酶（PAH）基因的突变引起的，该基因已经被描述了超过 600 种不同的突变。基因型-表型相关性是一种有用的工具，可以预测代谢表型，制定更适合的饮食方案，最近还可以评估 BH（4）治疗的潜在反应性，这是 PKU 领域的一个热门话题。本研究的目的是对南葡萄牙 HPA 人群的 PAH 基因进行分子分析，评估基因型-表型关系，并预测 BH（4）反应性。我们使用从外周血样本或 Guthrie 卡中提取的基因组 DNA 对 83 名 HPA 患者进行了分子特征分析。通过 PCR 扩增外显子和相关内含子边界，然后直接进行序列分析来扫描 PAH 突变。通过 PCR-RFLP 分析确定基因内多态性。结果能够对 67 名患者进行全面特征分析。突变谱包括 34 种不同的突变，最常见的是 IVS10nt-11G>A（14.6%）、V388M（10.8%）、R261Q（8.2%）和 R270K（7.6%），这四种突变占所有突变等位基因的 46%。此外，还鉴定了 12 种不同的单倍型，大多数突变与单一单倍型相关。值得注意的是，根据 BIOPKU 数据库，超过一半的 34 种突变属于已经在 BH（4）反应性患者中鉴定出的 70 多种突变之一。共发现 51 种不同的基因型组合，大多数在单个患者中发现，涉及 BH（4）反应性突变。综上所述，南葡萄牙 PKU 患者中有相当数量（30-35%）可能受益于 BH（4）治疗，这种治疗与较宽松的饮食相结合，或者在特殊情况下作为单一疗法，可能有助于减少营养缺乏，并最大限度地减少神经和心理功能障碍。
