中文摘要：

目的对一例46XY性发育异常的患者进行CYP17A1致病基因分析，并探讨新的突变对患者表型的影响。方法对患者及其父母的CYP17A1基因的8个外显子进行PCR扩增，扩增产物直接测序。将野生型和含有新突变位点的突变型PCR片段连入表达载体，构建Mini-gene系统，转染HEK-293T细胞，RT—PCR观察新突变位点对剪切的影响。进一步构建野生型和剪切异常的CYP17A1cDNA全长表达质粒，转染HEK-293T细胞，体外检测CYP17A1酶活性。结果基因分析显示患者的CYP17A1基因为复合杂合突变，其中一个等位基因为外显子6中c．985_987delinsAA突变，另一等位基因含有新的同义突变（c．1263G〉A：GCG〉GCA）。体外研究表明，这种同义突变会产生新的剪切位点，导致CYP17A1基因mRNA异常剪切，剪切产物中CYP17A1的415位氨基酸残基后缺失6或7个氨基酸。体外转染和酶活性检测证实异常剪切产物使酶活性丧失；但此突变对剪切的影响并不是完全的，在患者体内还应存在部分正常的剪切产物，发挥残余酶活性，与患者的表型相一致。结论本研究首次报道了由于CYP17A1基因外显子剪切突变导致的17α-羟化酶缺乏的患者，并且启动对异常剪切体的功能研究。

英文摘要：

Objective To analyze CYP17A1 gene mutation in a patient with 46, XY disordered sex development and to explore the possible influence on the phenotype of the patient. Methods Eight exons of CYP17A1 gene in the patient and her parents were amplified and directly sequenced. In order to construct Mini-gene system, PCR fragments containing wildtype and mutant splicing sites were inserted in expression vector, and then transfected into cells. RT-PCR was used to observe the influence of splicing site mutation. Wildtype and aberrant splicing CYP17A1 cDNA expression plasmids were constructed and transfected into cells respectively, and CYP17A1 enzyme activity was tested in vitro. Results Mutation analysis revealed compound heterozygous CYP17A1 mutations, with Y329fs in one allele and a synonymous substitution （c. 1263G〉A： GCG〉GCA）in another allele. In vitro analysis showed that the synonymous substitution induced a novel splicing site, which resulted in aberrant splicing of CYP17A1 mRNA and lacked six or seven amino acids after415 in splicing product. In vitro transfection and enzyme activity experiment showed that the aberrant splicing product abolished the enzyme activity completely. However, this mutation did not completely influence splicing. The patient also had a part of normal splicing product, which was a coincidence to the phenotype of the patient. Conclusion This is the first description of an exonic splicing mutation in CYP17A1 relevant to the 17α-hydroxylase deficiency phenotype. The functional study of the aberrant splicing variant has been initiated.