雄激素受体基因新突变引起的完全型雄激素不敏感综合征

目的 对1例完全型雄激素不敏感综合征(complete androgen insensitivity syndrom,CAIS)的雄激素受体(androgen receptor,AR)基因进行分析,寻找致病突变.方法 提取外周血全基因组DNA,扩增位于X染色体上的AR基因所有8个外显子及邻近外显子与内含子之间的剪切位点DNA序列,对扩增片段直接进行DNA序列测定,与基因库中的序列进行比对.结果 该病例AR基因第1外显子的441位密码子发生无义突变(GAA→TAA),由编码谷氨酸(Glu)变为终止密码,导致雄激素受体蛋白翻译至441位时终止,产生没有功能的氨基酸多肽残段.结论 Glu441stop(GAA→TAA)是一种导致CAIS的AR基因新的突变方式,之前在世界范围内均未见报道,丰富了AR基因突变谱,增加对CAIS发病机制的了解.     

雄激素受体基因新突变引起的完全型雄激素不敏感综合征

目的 对1例完全型雄激素不敏感综合征(complete androgen insensitivity syndrom,CAIS)的雄激素受体(androgen receptor,AR)基因进行分析,寻找致病突变.方法 提取外周血全基因组DNA,扩增位于X染色体上的AR基因所有8个外显子及邻近外显子与内含子之间的剪切位点DNA序列,对扩增片段直接进行DNA序列测定,与基因库中的序列进行比对.结果 该病例AR基因第1外显子的441位密码子发生无义突变(GAA→TAA),由编码谷氨酸(Glu)变为终止密码,导致雄激素受体蛋白翻译至441位时终止,产生没有功能的氨基酸多肽残段.结论 Glu441stop(GAA→TAA)是一种导致CAIS的AR基因新的突变方式,之前在世界范围内均未见报道,丰富了AR基因突变谱,增加对CAIS发病机制的了解.     

完全型雄激素不敏感综合征雄激素受体基因突变的鉴定与分析

目的 对l例完全型雄激素不敏感综合征(complete androgen insensitivity syndrome,CAIS)患者的雄激素受体(androgen receptor,AR)基因进行分析,寻找潜在的突变位点,并进一步分析其发病原因.方法 提取患者外周血全基因组DNA,扩增位于X染色体AR基因8个外显子及邻近外显子与内含子剪切位点DNA序列,对扩增产物直接进行DNA序列测定,与GenBank中的基因序列进行比对.结果 该患者AR基因在第6外显子核苷酸序列3507位点缺失一个碱基C而引起移码突变,致使在第808位密码子出现终止密码子(TGA)使得翻译提前终止形成截短的雄激素受体蛋白.该突变可能诱导雄激素受体结合能力发生功能上的变异,导致CAIS的发生.结论 AR基因第6外显子核苷酸序列3507位点缺失碱基C引起的移码突变是一种导致CAIS新的基因突变方式,该研究丰富了AR基因突变谱,为了解CAIS的发病机制提供了新的依据.     

雄激素受体基因剪接受点突变G3346→T引起一例完全型雄激素不敏感综合征

目的－探讨完全型雄素不敏感综合征（complete androgen insensitivity syndrome,cAIS)发病的分子机理,并研究雄激素受体（androgen receptor,AR)结构,功能及其与临床表现的关系。方法 用银染聚合酶链反应－单链构象多态性（polymerase chain reaction-single strand conformation polymorphism,PCR-SSCP)及PCR产物直接测序的方法,对1例完全型AIS患者AR基因外显子B－H分别进行了研究。结果 外显子F片段在SSCP分析时有泳动变位,经测序,突变发生在内含子5与外显子F交界处G^3346→T,结论 为首例发现的AR基因剪接受点突变,GU－AG的高度保守对于维持AR的正常功能非常重要。     

Liddle's syndrome caused by a novel mutation of the γ-subunit of epithelial sodium channel gene SCNN1G in Chinese

Objective To screen the mutation of the β and γ subunits of epithelial sodium channel gene SCNN1 in two families with Liddle's syndrome. Methods Two patients clinically diagnosed as Liddle's syndrome and their family members were enrolled. Peripheral blood samples were collected and total genomic DNA was prepared. Polymerase chain reaction (PCR) was used to amplify the exon 13 of the SCNN1B and SCNN1G gene. PCR products were purified and subjected to direct DNA sequencing. Results A heterozygous nonsense mutation at codon 564 of the SCNN1B gene from CGA(Arg) to stop codon(TGA)was detector in the proband of family 1. More importantly, a novel heterozygous nonsense mutation of CAG (Gln) to stop codon TAG at codon 567 of the SCNN1G gene was detected in the proband and another two members of family 2. Conclusion Screening for specific mutations of the SCNN1 gene in relatives of patients with Liddle's syndrome can be used to identify the previously unrecognized cases within the family.A new nonsense mutation(Q567X) of the SCNN1G gene is likely the cause of Liddle's syndrome in family 2.     

Liddle's syndrome caused by a novel mutation of the γ-subunit of epithelial sodium channel gene SCNN1G in Chinese

Objective To screen the mutation of the β and γ subunits of epithelial sodium channel gene SCNN1 in two families with Liddle's syndrome. Methods Two patients clinically diagnosed as Liddle's syndrome and their family members were enrolled. Peripheral blood samples were collected and total genomic DNA was prepared. Polymerase chain reaction (PCR) was used to amplify the exon 13 of the SCNN1B and SCNN1G gene. PCR products were purified and subjected to direct DNA sequencing. Results A heterozygous nonsense mutation at codon 564 of the SCNN1B gene from CGA(Arg) to stop codon(TGA)was detector in the proband of family 1. More importantly, a novel heterozygous nonsense mutation of CAG (Gln) to stop codon TAG at codon 567 of the SCNN1G gene was detected in the proband and another two members of family 2. Conclusion Screening for specific mutations of the SCNN1 gene in relatives of patients with Liddle's syndrome can be used to identify the previously unrecognized cases within the family.A new nonsense mutation(Q567X) of the SCNN1G gene is likely the cause of Liddle's syndrome in family 2.     

中国人圆锥角膜患者的TGFBI基因编码区点突变及多态性的检测和分析

Objective To investigate the point mutations and polymorphisms of transforming growth factor β-induced gene (TGFBI) in Chinese patients with keratoconus and discuss the relationship between the feature of gene mutations and single nucleotide polymorphisms of TGFBI gene and keratoconus. Methods Polymerase chain reaction-single strand conformation polymorphism and DNA direct sequencing were performed in 30 keratoconus cases and 30 healthy controls. All 17 exons of the TGFBI gene were analyzed for point mutations and single nucleotide polymorphisms. Results Totally two heterozygous nucleotide changes were identified in exon 12 of the TGFBI gene. The codon 535 is changed from GGA to TGA in 1 patient, leading to a substitution of glycine to a stop codon at the protein level (G535X). The codon 540 is changed from TTT to TTC in 2 patients and 1 control individual, resulting in a nonsense mutation (F54F),and is a single nucleotide polymorphism of the gene. Conclusion Mutation and polymorphisms of the TGFBI gene were detected in Chinese patients with keratoconus in this study. The results suggest that TGFBI gene might play an important role in the pathogenesis of keratoconus.     

中国人圆锥角膜患者的TGFBI基因编码区点突变及多态性的检测和分析

Objective To investigate the point mutations and polymorphisms of transforming growth factor β-induced gene (TGFBI) in Chinese patients with keratoconus and discuss the relationship between the feature of gene mutations and single nucleotide polymorphisms of TGFBI gene and keratoconus. Methods Polymerase chain reaction-single strand conformation polymorphism and DNA direct sequencing were performed in 30 keratoconus cases and 30 healthy controls. All 17 exons of the TGFBI gene were analyzed for point mutations and single nucleotide polymorphisms. Results Totally two heterozygous nucleotide changes were identified in exon 12 of the TGFBI gene. The codon 535 is changed from GGA to TGA in 1 patient, leading to a substitution of glycine to a stop codon at the protein level (G535X). The codon 540 is changed from TTT to TTC in 2 patients and 1 control individual, resulting in a nonsense mutation (F54F),and is a single nucleotide polymorphism of the gene. Conclusion Mutation and polymorphisms of the TGFBI gene were detected in Chinese patients with keratoconus in this study. The results suggest that TGFBI gene might play an important role in the pathogenesis of keratoconus.     

完全型雄激素不敏感综合征雄激素受体基因突变分析

目的 对完全型雄激素不敏感综合征一家系雄激素受体(androgen receptor,AR)基因进行突变检测;并对发现突变的基因进行分析.方法 应用PCR扩增、DNA序列测定等技术分析所有AR基因外显子及其邻近DNA序列片段;应用核苷酸内切酶诊断方法观察其是否存在于正常人群;应用跨物种比对方法探讨突变所在位置的保守性.结果 3例患者AR基因第4外显子均发生E681D(GAG→GAT)错义突变,患者母亲为此突变杂合子携带者;患者父亲未见异常;正常人群未发现AR基因E681D突变;681位谷氨酸在不同物种间高度保守.结论 AR基因E681D(GAG→GAT)突变可能是导致完全型雄激素不敏感综合征新的突变方式.     

男性不育症患者X染色体雄激素受体基因外显子1、3、4状态筛选研究

目的研究雄激素受体（androgen receptor,AR）基因与特发无精症之间的关系。方法运用分子生物学方法分别检测35名无精症患者和20名对照组正常男性雄激素受体基因的3个功能区的DNA片段,结果实验组患者和正常男性AR外显子1中（CAG）n重复数在11~27之间,两组无显著差别,35例无精症患者用PCR扩增出雄激素受体外显子3（exon3）片段35例（100%）和外显子4（exon4）片段34例（97.15%）,20名正常已生育男性扩增出AR外显子3（exon3）片段20例（100%）和外显子4（exon4）片段20例（100%）。结论（CAG）n基因多态性与男性精子生成障碍无相关性,exon4缺失通过影响靶细胞核的类固醇激素-受体结合物数量在精子发生中的作用需进一步探讨。     

一种导致完全性雄激素不敏感综合征的AR基因移码突变的鉴定

目的 对1个男性假两性畸形完全性雄激素不敏感综合征的家系雄激素受体(androgen receptor,AR)基因进行突变检测,并分析其致病原因.方法 用PCR扩增及DNA测序等技术分析男性假两性畸形先证者候选基因AR的外显子及外显子内含子接头序列,根据检测到的突变位点情况,检测患者及其家系其他成员的相应DNA区段的碱基序列.结果 先证者及其家庭成员共3例患者均为AR基因1910delA的移码突变.其母亲为AR基因突变杂合子,是此疾病的携带者.该突变导致AR基因的N637I(AAU→AUC)、L638*(CTG→TGA)改变,导致AR蛋白283个氨基酸的截短.正常人群未发现该移码突变,该突变尚未见文献报道.结论 基因水平确定了该家系为AR基因突变引起的完全性雄激素不敏感综合征男性假两性畸形家系,同时发现了1种AR基因病理性新突变.     

Analysis of exon 1 mutations in the androgen receptor gene

Eleven mutations in exon 1 of the androgen receptor gene (AR) have been identified in 15 individuals with Androgen Insensitivity syndrome (AIS). Nine of the mutations yield a stop codon directly, or due to a frameshift, in individuals with complete AIS (CAIS). One individual with CAIS had three different mutations in exon 1: one is nominally silent (Glu 211; GAG 995 GAA); two are missense (Pro 390 Arg and Glu 443 Arg). Five unrelated individuals with either CAIS, partial AIS (PAIS) or mild AIS (MAIS) had GAG 995 GAA as their only alteration. This report almost doubles the number of exon 1 mutations stored in the AR Mutation Database, reinforces their highly predominant nonsense character, and identifies Pro 390 and/or Gln 443 as residues that are probably necessary for one or more specific functions of the AR's N-terminal transactivation domain.     

Novel molecular defects in the androgen receptor gene of Mexican patients with androgen insensitivity

The androgen insensitivity syndrome (AIS) is an X-linked form of male pseudohermaphroditism caused by mutations in the androgen receptor (AR) gene. In the present study, we analyzed the AR gene in 8 patients, 4 sporadic and 2 familial cases with the syndrome, using exon-specific polymerase chain reaction, single-stranded conformational polymorphism and sequencing analysis and identified six new single base mutations, including one nonsense mutation at the hinge region of the receptor. These molecular lesions occurred in the steroid-binding domain (SBD) and all but one affected the first nucleotide of their respective codons. A nonsense mutation in exon 4, which converts a glutamine into a premature termination signal (Q657stop), a missense mutation changing arginine instead of glycine (G743R) and a conservative substitution of leucine with valine at amino acid 830 (L830V) were detected in patients with CAIS. Three other missense mutations located in exons 4 (L701I), 5 (A765S), and 6 (Q802R) were present in individuals bearing a partial form of AIS. These data allow us to reaffirm the view that nonsense mutations in the AR results almost invariably in a CAIS phenotype and underly the importance of the SBD for the AR functional activity.     

Androgen receptor gene mutations in 46,XY females with germ cell tumours

We present clinical findings and molecular characterization in two patients previously diagnosed as 46,XY female gonadal dysgenesis with germ cell tumour. Both patients showed a female general phenotype with unambiguously female external genitalia and primary amenorrhoea compatible with complete androgen insensitivity syndrome. The first patient, at the age of 31 years, developed a dysgerminoma measuring 8 x 13 x 10 cm in one abdominal testis. Genetic analysis revealed a single nucleotide substitution on exon 4 in the hormone-binding domain of the androgen receptor (AR) gene, resulting in a change of codon 681 GAG (glutamic acid) to AAG (lysine). The second patient, at the age of 17 years, developed a dysgerminoma measuring 12 x 10 x 7 cm in one abdominal testis and gonadoblastoma in the other testis. Genetic analysis showed a point mutation on exon 3 in the DNA-binding domain of the AR gene resulting in a change of codon 607 CGA (arginine) to CAA (glutamine). Arg607-Gln and Arg608-Lys point mutations in the DNA-binding domain of the AR gene have been associated with male breast cancer in partial androgen insensitivity syndrome. A codon 607 mutation in the DNA-binding domain of the AR gene in our patient 2 is associated with early development of germ cell tumour. We suggest regular molecular genetic analysis of the AR gene in 46,XY females with germ cell tumour and androgen insensitivity syndrome to detect differences in the specific regions of AR gene involved in early progression toward oncogenesis of the dysgenetic gonads.     

Five novel androgen receptor gene mutations associated with complete androgen insensitivity syndrome

Mutations in the androgen receptor (AR) gene result in androgen insensitivity syndrome (AIS). We have identified five novel mutations that result in a complete loss in AR function and are associated with complete AIS. The mutations span all three AR major functional domains. In two cases, the loss of AR function could be explained on the basis of the current knowledge of AR molecular structure and function. N-terminal mutation c.256C>T (p.Gln86X) leads to an early stop codon and abolishes all DNA and ligand binding. The DNA-binding domain mutation c.1685G>A (p.Cys562Tyr) is located in the N-terminal part of the first zinc finger; a mutation in this position is likely to impair the association of the mutated AR with the androgen response element of target genes. The splice site mutation at intron 2/exon 3 junction (c.1766-1G>A) is shown to lead to c.1765_1766 ins69 (p.[Gly589_Lys590ins23;Gly589Glu]). The two novel ligand-binding domain mutations identified were recreated by site-directed mutagenesis. Both mutations c.2171G>T (p.Gly724Val) and c.2435T>C (p.Leu812Pro) abolished AR ligand binding and severely impaired AR mediated transactivation. Residue p.Gly724 is located in the ligand binding domain, between helices 3 and 4. This region is known to be involved not only in ligand binding but also in AR N/C-terminal interactions. The mutation p.Leu812Pro is located in the C-terminal end of helix 8. This domain is highly conserved and critical for ligand binding. This study extends current understanding of AR mutations associated with CAIS.     

A novel point mutation (R840S) in the androgen receptor in a Brazilian family with partial androgen insensitivity syndrome

Mutations of the androgen receptor gene causing androgen insensitivity syndrome in 46, XY individuals, result in phenotypes ranging from complete female to ambiguous genitalia to males with minor degrees of undervirilization. We studied two Brazilian brothers with partial androgen insensitivity syndrome. They were born with perineal hypospadias, bifid scrotum, small penis and cryptorchidism, and developed gynecomastia at puberty. Genomic DNA was extracted and denaturinggradient gel electrophoresis of exon 7 of the androgen receptor gene followed by sequence analysis revealed a new mutation, a C A transversion, altering codon 840 from arginine (CGT) to serine (AGT). R840 is located in the androgen binding domain, in a “hot spot” region, important for the formation and function of the hormone receptor‐complex and within the region that is involved in androgen receptor dimerization. Replacement of arginine (basic) by serine (neutral and polar) is a nonconservative substitution. Three mutations in this residue (R840C, R840G nonconservative and R840H, conservative) were previously reported in patients with partial androgen insensitivity syndrome and when expressed “in vitro” lead to a subnormal transactivation of a reporter gene. We conclude that the novel R840 mutation in the androgen receptor is the cause of partial androgen insensitivity syndrome in this Brazilian family. Hum Mutat 14:353, 1999. © 1999 Wiley‐Liss, Inc.     

Rapid detection of a mutation hot-spot in the human androgen receptor

Mutations of the human androgen receptor gene may disturb sexual development in males, and are inherited as an X-linked recessive trait. The vast majority of the mutations are familial. We have identified a large kindred with complete androgen insensitivity syndrome (CAIS) without detectable androgen-binding in genital skin fibroblasts. A single nucleotide substitution (C-to-T transition) was identified, resulting in an Arg⁸⁵⁵ to Cys in the androgen binding domain. To date, four independent CAIS families have been reported with this specific mutation that coincides with the propensity of cytosines at CpG dinucleotides to methylate. An allele-specific oligo-nucleotide assay was developed that allowed for the rapid and specific identification of this mutation hot-spot in individuals with androgen receptor incensitivity syndromes.