Garcia M G, Torres R J, Puig J G
Divisions of Clinical Biochemistry and Internal Medicine, La Paz University Hospital, Madrid, Spain.
Nucleosides Nucleotides Nucleic Acids. 2010 Jun;29(4-6):301-5. doi: 10.1080/15257771003738675.
Lesch-Nyhan syndrome is an X-linked recessive inborn error of metabolism due to a complete deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) activity (OMIM 300322). Partial deficiency of HPRT (OMIM 300323) is characterized by the effects of excess uric acid synthesis and a continuum spectrum of neurological manifestations, without the manifestations of full-blown Lesch-Nyhan syndrome. Both diseases have been associated with mutations in the HPRT1 gene. We have described one Lesch-Nyhan patient and four partial HPRT deficient patients with a normal HPRT1 coding region. These patients showed markedly decreased HPRT mRNA expression, but no mutation in their genomic regulatory sequences from HPRT1 gene. In this study, we analyzed the promoter region methylation status of the HPRT1 gene in these five HPRT deficient patients.
DNA was bisulphite modified and a 620 bp fragment including 320 bp 5' to start codon was amplified and sequenced. The methylation status of 35 CpG island 5' to start codon and 28 CpG island 3' to start codon were investigated in male controls, female controls, patients, and the patient's mothers. Primer pairs were designed for methylated-specific and unmethylated-specific amplification and PCR was performed employing DNA bisulphite treated as template.
No alterations in the methylation pattern of the HPRT1 promoter were found in the five HPRT deficient patients.
The promoter region methylation status of these five HPRT deficient patients was similar to that of normal subjects. Thus, some other genetic alteration must explain a reduced enzyme activity with a normal gene coding region.
莱施-奈恩综合征是一种X连锁隐性代谢性遗传病,由次黄嘌呤-鸟嘌呤磷酸核糖转移酶(HPRT)活性完全缺乏引起(OMIM 300322)。HPRT部分缺乏(OMIM 300323)的特征是尿酸合成过多的影响以及一系列连续的神经学表现,而无典型莱施-奈恩综合征的表现。这两种疾病均与HPRT1基因突变有关。我们描述了1例莱施-奈恩患者和4例HPRT部分缺乏患者,其HPRT1编码区正常。这些患者的HPRT mRNA表达明显降低,但HPRT1基因的基因组调控序列未发现突变。在本研究中,我们分析了这5例HPRT缺乏患者中HPRT1基因启动子区域的甲基化状态。
对DNA进行亚硫酸氢盐修饰,扩增并测序一个包含起始密码子上游320 bp的620 bp片段。在男性对照、女性对照、患者及其母亲中研究起始密码子上游35个CpG岛和下游28个CpG岛的甲基化状态。设计甲基化特异性和非甲基化特异性扩增引物对,以亚硫酸氢盐处理的DNA为模板进行PCR。
5例HPRT缺乏患者的HPRT1启动子甲基化模式未发现改变。
这5例HPRT缺乏患者的启动子区域甲基化状态与正常受试者相似。因此,一定存在其他遗传改变来解释基因编码区正常但酶活性降低的现象。