苯丙氨酸羟化酶缺乏症家系PAH基因新发突变分析

目的 对一个苯丙氨酸羟化酶缺乏症(phenylalanine hydroxylase deficiency,PAHD)家系苯丙氨酸羟化酶(phenylalanine hydroxylase,PAH)基因进行突变位点检测和分析,探讨此家系发病原因。方法 采用二代测序技术(next generation sequencing,NGS)和多重连接探针扩增技术(multiplex ligation-dependent probe amplification,MLPA)对先证者及其父母的静脉血进行PAH基因组测序和外显子缺失、重复分析。结果 先证者找到1个错义突变和1个剪接缺失,分别为:第6外显子c.630T>G和第2外显子c.61-1G>A,这两个变异在人类基因突变数据库(Human Gene Mutation Database,HGMD)中未见报道,根据美国医学遗传学与基因组学学会(America College of Medical Genetics and Genomics, ACMG)指南判定为临床意义未明和疑似致病性变异;信息软件REVEL预测结果为有害和未知。采用MLPA对先证者进行外显子缺失、重复分析显示PAH基因外显子拷贝数未发现异常。结论 PAH基因6号外显子c.630T>G和2号外显子c.61-1G>A可能是该PAHD家系的致病突变。

Analysis on de novo mutations in PAH genes of the family with phenylalanine hydroxylase deficiency

Objective To investigate the pathogenesis of a family with phenylalanine hydroxylase deficiency (PAHD) by detecting and analyzing the mutation sites of phenylalanine hydroxylase (PAH) genes of the family. Methods PAH genome sequencing and exon deletion or duplication analysis were performed in the venous blood of probands and their parents by the next-generation sequencing (NGS) and multiplex ligation-dependent probe amplification (MLPA). Results The proband was found to have one missense mutation and one splice deletion, namely c.630t > G in Exon 6 and c.61-1G > A in Exon 2, respectively, which were not reported in Human Gene Mutation Database (HGMD), and were determined as clinically unknown and suspected pathogenic variants in America College of Medical Genetics and Genomics (ACMG) guidelines. The two mutations were predicted to be harmful and unknown in prediction results of information software REVEL, and no abnormal copy number of exon of PAH gene was found in the exon deletion and duplication analysis on the proband by using MLPA. Conclusion Exon 6 c.630T > G and exon 2 c.61-1G > A of PAH gene may be pathogenic mutations of PAHD in the family.