46,XY女性患者SRY基因启动子区域的突变分析

大约15%的46,XY女性患者中发现SRY基因编码区突变,其他患者可能是SRY基因的调节区, 包括启动子区域发生了突变,或者其他相关基因发生突变所致。本文采用限制性酶切、PCR-SSCP及银染检测技术,对7例患者SRY基因的启动子区域进行了突变筛查, 结果未发现异常,提示这些患者的病因与SRY基因启动子区域本身无关,结合对患者SRY基因HMG基序DNA的突变分析结果,表明除SRY基因异常外还存在其他导致46,XY女性性反转综合征的遗传机制。 Abstract:Using restriction endonuelease digestion and PCR-SSCP with silver staining,we analyzed the promotor region of SRY gene in seven 46,XY femalcs.The results showed no abnormality,thus ruling out the mutations in the promotor region of the SRY gene as a possible cause of sex reversal in these XY females.In view with the absence of the mutations in the HMG regions of the SRY genes of several patients,it is suggested that SRY gene is not the only gene responsible for testicular development but is one of many hierarchical genes involved in a genetic cascade for sexual differentiation.     

46,XY女性性反转患者SRY基因的两个新突变类型

Y染色体上的性别决定区域——SRY基因作为睾丸决定因子,可以调控男性性别发育过程。SRY基因是一种转录因子,属于带有高迁移率族蛋白家族,该家族成员包含能与DNA结合的HMG盒基序。已知SRY基因的缺失和点突变是造成XY女性性反转的病因之一。通过筛查10位中国46,XY女性性反转病人SRY基因的开放阅读框区域,探寻新的突变类型。用标准方法从外周血中抽提gDNA,通过聚合酶链式反应扩增SRY基因中部的609bp的DNA片段。扩增后的PCR片段被克隆到pUCm-T载体中,在ABI377-3自动测序仪上完成测序。运用限制性内切酶酶切分析的方法验证DNA测序的结果。结果表明,在两个患者的SRY基因中分别发现了新的核苷酸点突变,并都导致氨基酸替代。一个突变发生在SRY基因的5’端HMG盒外的核苷酸第113位腺嘌呤(A)被鸟嘌呤(G)取代,并导致谷氨酸被甘氨酸替换;另一个突变是第387位核苷酸发生T被A替换,该突变引起第129位的酪氨酸变成终止密码,她父亲的SRY序列被证明是正常的野生型。通过查询文献和人类基因突变数据库(HGMD),这两个突变都是以前未见报道过的新型SRY基因突变,并使因核苷酸替换引起SRY基因突变总数增加到45。     

哺乳动物性别决定基因的研究进展

哺乳动物的性别发育经历了个连续不同时期;受精时期性染色体的构建（XY或XX）;性腺发育和分化（精巢或卵巢）;获得恰当的性别表现型（雄性或雌性）。人们已经发现睾丸决定因子（Testis determining factor）就是SRY（Sex determining region on Y chromosome）,并逐渐确定了其他与性别决定和性别反转相关的基因,如SOX9,DAX1,SF1,WT1,GATA-4等。综述了与哺乳动物性别控制有关的基因研究进展。     

一个46,XY"女性"不育症家系的遗传学分析

运用常规的染色体G带分析和基因分析技术对-46,XY男性女性化家系进行遗传学分析,发现：先证者及其妹妹的染色体核型为46,XY,其母亲和父亲的核型正常;对睾丸决定基因（SRY）和雄激素受体基因（AR）进行突变检测,在SRY基因的整个编码区中没有发现突变,而AR基因的第7个外显子的第840个密码子由CGT（编码精氨酸）变为CAT（编码组氨酸）,这一改变可能是导致核型为46,XY女性化而发生不育。     

一新型SOX9基因致病性突变:R178L(G→T)

人SOX9基因同时参与胚胎骨骼形成和睾丸发育调控．对一例多发畸形的早产女性胎儿进行SRY基因扩增和SOX9基因突变分析,发现其具有男性特异性SRY基因,且SOX9基因发生R178L(G→T)的突变,提示该病例为SOX9基因突变导致的广泛性先天发育不良合并常染色体男一女性性反转．该突变此前未见报道,这也是中国人群中首次报道致病性SOX9基因突变。     

医学遗传学的一个重要问题——两性畸形

本文报告各种类型的两性畸形19例,其中包括46,XX女性假两性畸形10例,46,XY/45,XO男性假两性畸形2例,46,XY完全型睾丸女性化2例,46,XY不完全型睾丸女性化2例,假阴道会阴囊尿道下裂综合症工例,46,XY无性腺症1例,和46,XX/46,XY真两性畸形1例。两性畸形的正确诊断要依靠临床检查、内分泌检查和染色体检查,综合而作出诊断。本文对于两性畸形的分类、诊断、鉴别诊断和治疗进行了讨论。     

中国人SRY基因的分离、克隆和核苷酸序列分析

睾丸决定因子基因(Testis-determining factor,TDF)位于Y染色体短臂上,它的表达产物诱导睾丸组织的发生。SRY基因(Sex-determining Region of the Y)位于Y染色体的性别决定区内,许多特征显示SRY就是TDF。我们选用与SRY基因相应的引物,用PCR技术对正常人男女各10例的基因组DNA进行扩增。将特异扩增的男性SRY基因片段重组到质粒PUC12中,得到含有中国人SRY基因片段的克隆,命名为PSY-1、PSY-2。用[~(32)p]标记重组质粒中的SRY基因片段作探针,与PCR结果进行Southern杂交,男性样品均显示特异杂交带,女性样品为阴性。用末端终止法测定克隆的SRY基因片段的全部核苷酸序列为299bp,含有SRY基因中高度保守及功能特异性区域的240bp,我们对此进行了讨论。     

无精和严重少精症患者的遗传缺陷分析——-附2例世界首报染色体异常核型

对217例无精和严重少精症患者外周血淋巴细胞染色体核型进行分析,并采用聚合酶链反应对7例Y染色体结构异常患者的AZFc区进行检测。发现187例无精症患者中检出异常核型77例（41.18%）（其中46,XY,t(6;14)(p21;p13),46,XY,t(8;12)(p21;q24)为世界首报核型）,主要涉及染色体异常（数目异常和结构异常）;染色体异态（Y染色体异态和9号染色体臂间倒位）及46,XX性反转;30例严重少精症患者中检出异常核型4例（13.33%）（结构异常和46,XX性反转）。由此可见,性染色体数目和结构异常是精子发生障碍的主要原因,其次常染色体的某些断裂点也可能影响精子发生。AZFc区的缺失与否与精子发生也有直接关系。     

应用多重PCR技术检测性器官异常患者的性别决定基因

采用针对人SRY基因及X与Y染色体同源序列的两对引物进行多重聚合酶链反应技术检测204例新生儿脐血DNA,男性均显示590bp、 355bp及280bp 3条扩增带,女性只有590bp1条扩增带,性别鉴定准确率为100%。又检测47例性器官异常患,13例社会性别为女性者只出现590bp扩增带,与核型性别结果一致。 34例社会性别为男性者中,有2例SRY基因检测结果阴性,只出现590bp带,核型为46,XX,证明这两例患者社会性别不相符,经病理证实后应诊断为女性假两性畸形。 Abstract:This investigation adapted multiplex PCR technique with two pairs of primer to determine sex according to the human SRY gene and X,Y chromosome analogical sequence.We detected bellybutton blood DNA from 204 newborns.Male revealed three bands:590bp,355bp and 280bp,and females only had one band which was 590bp,the accuracy of sex determination was 100%.47 sexual abnormal patients were tested.The results showed that 13 cases,whose social sex were female,had one 590bp band which consistent with their chromosome type sex.In the rest 34 cases,whose social sex were male,2cases showed,on the contrary,only one 590bp band and their chromosome type were 46,XX.This proved that the two patients did not consistent with their social sex,and pathological analysis showed that they were female pseud-hermaphroditism.     

Lyon假说的应用及其局限性

人类体细胞中共有 46条染色体 ,其中 1～ 2 2对为常染色体 ,另 1对为性染色体。在这些染色体上分布着大量的基因。人类体细胞中常染色体是成对存在的 ,其上的基因也总是成对存在的。若成对的基因失去 1个 ,则将对发育造成极为不利的影响。例如 ,5P- 综合征(又称猫叫综合征 ) ,其核型为 46,XX(XY)del(5 ) (P15) ,分析患者的核型 ,成对的第 5号染色体中的 1条比正常的短 ,主要是缺失了其短臂的一部分 ,即该部位的基因是成单存在的。再比如 ,1 8 三体综合征 (又称爱德华综合征 ) ,患者核型为 47,XX(XY) ,+1 8,其核型分析表明 ,患者的 1 8号…     

Absence of Y-specific DNA sequences in human 46,XX true hermaphrodites and in 45,X mixed gonadal dysgenesis

Summary A search for Y-specific DNA sequences has been performed in a sample of seven 46,XX true hermaphrodites and one 45,X mixed gonadal dysgenesis case and compared with a sample of 11 XX males. Using six Y-specific DNA probes no hybridization signal was obtained in the hermaphrodite group; in contrast, all XX males gave a positive signal with at least one probe. This difference is statistically highly significant. We conclude that the aetiology of true hermaphroditism is different from that of the XX male syndrome. As all cases of the hermaphrodite group are positive for the serological sex-specific antigen (Sxs) it is concluded that this antigen can be present even in the absence of Y-specific DNA.     

Deletion mapping of the testis determining locus with DNA probes in 46,XX males and in 46,XY and 46,X,dic(Y) females.

Eleven Y-specific DNA probes hybridizing with DNA from one or more 46,XX males were isolated from a recombinant phage DNA library constructed from flow sorted human Y chromosomes. Two probes hybridized with DNA from nine out of eleven, i.e. greater than 80% of these 46,XX males. The relative frequency of hybridization of the probes in the 46,XX males and in a 46,X,dic(Y) female, together with in situ hybridization data, allowed mapping of the probes on Yp in relation to a putative testis determining locus. Several of those probes were also absent in a 46,XY female, further refining a model for ordering the probes on Yp. The DNA of one XX male hybridized both with probes from Yp and probes from proximal Yq (excluding the pericentral region). This suggests that complex translocations may occur into the DNA of 46,XX males that involve not only parts of Yp but also parts of Yq.     

Genetic analysis of 38XX males with genital ambiguities and true hermaphrodites in pigs

In pig, the frequency of intersexuality ranges from 0.1 to O.6%, depending on the breed. In a closed pig herd at INRA an intersex condition was observed in 0.75% of ‘females’. The present study describes 11 animals with a 38XX karyotype and the presence of testicular tissue. Phenotypically, all presented with abnormal external or/and internal genitalia. Southern blot analysis with Y-specific probes (SRY and ZFY) revealed the absence of Y material in all animals tested. By polymerase chain reaction (PCR) amplification, 10 of 11 intersex pigs lacked the SRY gene in gonad DNA. These data are compatible with an autosomally (or pseudoautosomally) determined mechanism. Moreover, analysis of familial cases seemed to indicate that 38XX male pseudohermaprodites and 38XX true hermaphrodites may represent alternative manifestations of the same genetic defect.     

The sole presence of the testis-determining region of the Y chromosome (SRY) in 46,XX patients is associated with phenotypic variability.

Four cases of XX patients with testis development are reported. The aim of this study was to describe their clinical features and to see if there was any relationship between phenotypes and the presence of Y material. Several human Y-derived sequences including the SRY probe were used to analyze the DNA of the patients. Yp material including the pseudo-autosomal region and SRY was detected. The cases reported in this study confirm that XX true hermaphrodites cannot be distinguished from XX males on the basis of their genotypes. There is no relationship between clinical and anatomical phenotypes and the presence of Y material. SRY does not warrant a complete and normal testis differentiation. Although similar in some features with Klinefelter's syndrome patients, XX males exhibit specific clinical manifestations due to the lack of Y-specific genes.     

Molecular cytogenetic analysis of XX males using Y-specific DNA sequences,including SRY

Summary XX maleness is the most common condition in which testes develop in the absence of a cytogenetically detectable Y chromosome. Using molecular techniques, it is possible to detect Yp sequences in the majority of XX males. In this study, we could detect Y-specific sequences, including the sex-determining region of the Y chromosome (SRY), using fluorescence in situ hybridization. In 5 out of 6 previously unpublished XX males, SRY was translocated onto the terminal part of an X chromosome. This is the first report in which translocation of an SRY-bearing fragment to an X chromosome in XX males could be directly demonstrated.     

Investigation of three XX males by cytogenetic and DNA analyses

Summary We report cytogenetic and DNA studies in three XX males. Two males seemed to have extra chromosomal material on the tip of one X chromosome. All three males were shown to have Y chromosome material as indicated by hybridization of Y-specific DNA probes to genomic DNA. One male was unusual in that as he showed the 15-kb fragment detected by pDP34 that is thought to map close to the Y centromere. It is suggested that this finding might point to an inversion on the Y chromosome.     

Identification of a case of Y:18 translocation using a Y-specific repetitive DNA probe

Summary We have used a recombinant DNA clone derived from the Y-specific 3,4-kb repeats for in situ chromosome hybridization and Southern blotting analysis to identify a case of de novo Y;18 translocation. The proband has a chromosome complement of 46,XY and a variant chromosome 18 with a Q-bright and C-positive short arm. The father has a normal male karyotype of 46,XY. The mother has a female karyotype of 46,XX and an unusually large Q-bright satellite on one chromosome 22. In situ hybridization with the 3,4-kb probe to the metaphase preparations of family members indicated that the additional Q-bright material in the proband's variant chromosome 18 derived from the Y chromosome of his father, and not from the variant chromosome 22 of his mother. On Southern hybridization, the proband had approximately twice the amount of 3,4-kb repeats per cell as his father. These observations suggest a de novo genetic rearrangement in the proband which probably occurred during the father's spermatogenesis.     

Molecular analysis of the Y chromosome in XX sex-reversed patients

Molecular genetic analysis was performed for 26 phenotypically male patients lacking the Y chromosome in the karyotype. The sex-determining region Y (SRY) gene was found in 77% of the patients. PCR analysis of Y-specific loci in the 17 SRY-positive patients revealed Yp fragments varying in size in 16 cases and cryptic mosaicism (or chimerism) for the Y chromosome in one case. The frequencies of class I, II, and III (Yp+)XX sex reversals were 18.75, 25.25, and 56%, respectively. All of the class III (Yp+)XX sex-reversed patients had a 3.5-Mb paracentric inversion flanked by inverted repeats 3 (IR3) on the short arm of the Y chromosome.     

Quantitation of fetal DNA in maternal serum in normal and aneuploid pregnancies

We investigated whether the amount of circulating cell-free fetal DNA in maternal serum is influenced by fetal karyotype, using real-time quantitative polymerase chain reaction assay. Serum samples were obtained from pregnant women at gestational ages ranging from 15 to 17 weeks, prior to their undergoing amniocentesis. In total, we examined 70 samples consisting of 55 cases of pregnancy with 46,XY, 5 cases with 47,XY,+21, 3 cases with 47,XY,+18, a single case with 46,XY,dup(1) and 2 cases with twins of 46,XY, and 4 cases with 46,XX which were used as negative controls. We measured the concentration of the SRY sequence as a molecular marker for fetal DNA. The SRY sequence was detectable and measurable when the fetuses were male except for one case with 47,XY,+18. This case showed fetal growth retardation and bradycardia. No amplification signals of the SRY sequence were detected when the fetuses were female. The mean concentration of fetal DNA in maternal serum was 31.5 copies/ml in the pregnancy with 46,XY, 23.5 copies/ml in the pregnancies with 47,XY,+21 and 21.5 copies/ml in the pregnancies with 46,XY,+18. There were no significant differences in the concentration of fetal DNA between pregnancies with fetuses of normal karyotype and those with fetuses of abnormal karyotype.     

Sry-negative XX sex reversal in the American cocker spaniel dog

The Sry gene product serves an important function in male sex determination through testis induction. However, testicular development has been reported in SRY-negative XX sex reversed humans. XX sex reversal of the American cocker spaniel, inherited as an autosomal recessive trait, may be a homolog of this disorder. The purpose of this study was to determine whether the Sry high mobility group (HMG) box is present in genomic DNA of affected dogs. Conserved Sry HMG box and hypoxanthine phosphoribosyltransferase (HPRT) sequences were used as primers in polymerase chain reactions. A 167 bp Y-specific canine Sry HMG box sequence was cloned from genomic DNA of normal male dogs. Internal primers generated a 104 bp Sry HMG box product from normal males, but not from females or XX sex reversed dogs. Parallel reactions generated an HPRT product from all dogs. Results indicate that the Sry HMG box is absent in genomic DNA of XX sex reversed dogs. We speculate that activation of the testis differentiation cascade in the absence of Sry in this model is due to a mutant autosomal gene. © 1995 Wiley-Liss, Inc.