中国南方三个Hunter综合征家系的病因学研究

The Etiological Study of Three Hunter Syndrome Families in Southern China

【目的】揭示中国南方3个Hunter综合征家系的分子发病机制,阐明患者表型和基因型的相关性,为今后的产前或植入前基因诊断奠定基础。【方法】在临床初诊和系谱分析的基础上,首先进行尿糖胺聚糖定性检测,然后抽取患儿及其亲属的抗凝血,提取DNA并通过PCR、Sanger测序对IDS基因进行序列分析。对发现的新变异采用RT-PCR和生物信息分析等多种方法进行致病性鉴定。【结果】3个家系的患者尿检结果均为强阳性(++)。家系1~3先证者为男性,IDS基因均发生半合子突变且突变均来自其母,突变位点分别为:c.615_622delCATACAGT,c.847_848delGT和IVS7 ds+1 G>A。跨物种保守性分析结果显示IDS基因突变部位所在的氨基酸在物种进化过程中具有高度保守性。与正常蛋白相比,突变蛋白的高级结构预测结果存在明显差异。根据ACMG标准,3个家系的变异均为致病性突变。【结论】先证者所患疾病为Hunter综合征,IDS基因的c.615_622del(p.Ile206Valfs*18)、c.847_848del(p.Val283Alafs*57)和IVS7 ds+1 G>A(p.G336Dfs*12)均是新的致病性突变,它们是引起患儿发病的内在原因。本研究进一步丰富了IDS基因的突变谱。

【Objective】To reveal the molecular pathogenesis of Hunter syndrome in three families in southern China and to clarify the correlation between phenotype and genotype,so as to lay a foundation for future prenatal or preimplantation genetic diagnosis.【Methods】On the basis of initial clinical diagnosis and pedigree analysis,qualitative detection of glycosaminoglycans in urine was performed first,and then anticoagulant blood samples were collected from the children and their relatives.DNA was extracted and the IDS gene sequence was analyzed by PCR and Sanger sequencing.Various methods such as RT-PCR and bioinformatics analysis were used to identify the pathogenicity of the new variants.【Results】The urine test results of the patients in the three families were all strongly positive(++).Probands were all male,with hemizygous mutations in IDS gene from their mothers,and the mutation sites were c.615_622delCATACAGT,c.847_848delGT and IVS7 ds+1 G>A,respectively.The cross-species conservation analysis showed that the amino acid of IDS gene mutation site was highly conserved during species evolution.Compared with the normal protein,mutant proteins exhibited sig nificant differences in the predicted results of advanced structure.The variants identified in the three families were classified as pathogenic by ACMG criteria.【Conclusions】The three probands were diagnosed with Hunter syndrome.The c.615_622 del(p.Il 206 Valfs*18),c.847_848 del(p.Val 283 Alafs*57)and IVS 7 ds+1 G>A(p.G 336 Dfs*12)of IDS gene are all novel pathogenic mutations,which are the underlying causes of morbidity in children.This study has further enriched the mutation spectrum of IDS gene.