特发性无精子症少精子症患者分子遗传学及血清学的研究进展

由于生精障碍造成男性不育的因素占2%～4%,其中60%是由遗传因素造成.Y染色体微缺失与特发性无精子症少精子症关系的研究,确定了部分与生精过程相关的基因,并研究了部分基因的缺失与患者临床表现的关系.部分无精子症少精子症患者通过ICSI解决了生育问题,但已证实生精基因的缺失可传给其男性后代.因此通过对男性不育患者进行基因的检测,明确不育病因,给患者以明确的遗传咨询,指导生育是必要的.     

AZF基因微缺失与男性不育研究进展

由于基因缺陷所引起的生精障碍是导致男性不育的重要原因之一。其中,Y染色体无精症因子（azoospermia factor,AZF）区域微缺失与男性不育密切相关,是最常见的导致无精症与严重少精症的分子遗传病因。本文旨对AZF基因微缺失与男性不育研究进展作一综述。     

Y染色体单倍组与AZFc部分缺失

不育的夫妇约占育龄夫妇总数的10%～15%,其中男性因素约占50%以上。染色体畸变与Y染色体AZF微缺失是已知的两个主要的男性不育遗传学病因。近年来研究提示AZFc区的一些部分缺失类型可能是男性不育的高风险因子,且其生精表型与Y染色体单倍组存在关联。本文拟从Y染色体单倍组构成的遗传背景方面,综述Y染色体单倍组在AZFc区部分缺失及男性不育的发生中所起的作用。     

广西地区男性不育患者Y染色体微缺失结果分析及遗传效应

目的探讨广西地区男性不育患者Y染色体微缺失结果情况和临床遗传效应。方法采用染色体技术、PCR技术等对2180例男性不育患者进行外周血染色体分析及Y染色体微缺失6个系列标签位点检测。结果 2180例样本Y染色体AZF基因检测和Y染色体异常分别为总缺失率为6%（130/2180）和3.3%（71/2180）。同时发现Y染色体AZF基因缺失在生精障碍组与正常组、不孕产史组具有统计学意义;Y染色体核型以小Y和染色体多态性常见。结论男性不育患者与Y染色体微缺失及细胞核型所表现临床遗传效应密切相关,对于生殖异常的男性行外周血染色体检查和AZF微缺失检测有助于明确其遗传学病因,更好的为患者提供病因诊断、遗传咨询和治疗方案。     

特发性无精症和严重少精症患者Y染色体无精子因子的微缺失检测

生精障碍是男性不育的主要原因。研究发现，位于Y染色体长臂上存在着被称为无精子因子(azoospermia factor，AZF)的基因，它的DNA微缺失可以导致男性生精障碍所致的男性不育症。本文报道采用PCR方法对65例特发性无精症或严重少精症患者进行Y染色体的AZF基因微缺失的检测结果。     

Y染色体长度变异和微缺失与男性不育症关系探讨

目的探讨男性不育症患者Y染色体长度变异的临床意义及与男性生精障碍的关系。方法对2012年1月-2017年10月在我院门诊就诊的1864例男性不育症患者行外周血染色体核型分析和精液常规检测。结果在1264例男性不育症患者中检出Y染色体长度变异核型82例,占6.49%。(1)小Y(Y≤21号染色体)共44例,占53.66%;(2)大Y(Y≥18号染色体)共38例,占46.34%。Y染色体长度变异患者的无精子症和少弱精子症的发生率明显高于健康对照组,差异具有统计学意义(P0.01)。Y染色体长度变异患者的精子密度明显低于健康对照组,差异具有统计学意义(P0.01),精液量二组无差异。82例Y染色体长度变异患者进行AZF微缺失检查,发现有24例存在微缺失,检出率29.27%,其中最常见的为AZFc完全缺失检出10例,占12.20%。结论 Y染色体长度变异和微缺失可能是导致男性不育和精子生成障碍的重要原因。     

Y染色体与常染色体易位的遗传学分析及文献学习

目的探讨Y染色体与常染色体易位所产生的遗传效应,为男性不育遗传咨询及治疗提供依据方法回顾性分析8400例不孕不育患者,其中14例为Y染色体与常染色体易位,同时进行Y染色体微缺失检测,并辅以文献学习结果14例Y-常染色体易位中9例为46,XX／46,XY,der（15）t（Y;15）占Y-常染色体易位的64．3％,其余为Y-非近端着丝粒染色体易位,未发现合并Y染色体微缺失。结论1．Yq12与近端着丝粒染色体短臂易位,通常不引起表型和生育问题。2．Y染色体与非近端着丝粒染色体易位,会导致减数分裂异常,造成严重的生精障碍,产生无精子症和严重少弱精,从而引起男性不育。     

呼和浩特地区209例无精子症和严重少弱精子症患者的遗传因素调查

目的探讨染色体数目和结构异常,以及Y染色体无精子因子基因拷贝缺失与男性不育的关系。方法利用染色体G显带和PCR检测技术,对209例无精症和少弱精症患者进行外周血染色体检查,对在染色体核型分析中Y染色体部分缺失患者5例,11例小Y患者,以及1例Y染色体数目和结构均有异常的嵌合体患者,共17例进行Y染色体微缺失检测。结果共发现染色体异常核型71例,占34.9%。Y染色体微缺失患者4例。结论在无精症和少弱精症患者中存在较高频率染色体数目和结构异常,以及无精子因子基因拷贝缺失,遗传因素是造成男性不育的重要因素。     

618例不育男性的AZF基因微缺失分析

目的研究Y染色体AZF基因微缺失与男性不育的关系。方法应用多重PCR对618例男性不育患者进行Y染色体AZF基因的15个位点进行检测。结果一共检出Y染色体微缺失患者23例,占受检人群的3．72％,其中包括16例AZFc全部缺失、3例为AZFb＋c部分／全部缺失、3例为AZFa部分缺失和1例AZFa、AZFb、AZFc和AZFd四个区15个检测位点全部缺失。AZFc全部缺失患者中,中度至重度少精症13例,无精症3例;AZFb部分／全部缺失患者中,严重少弱精1例,无精症2例;AZFa部分缺失患者和15个位点全部缺失患者均为无精症。结论Y染色体AZF基因微缺失是男性不育的重要原因之一,该检测可为患者的诊断、治疗及遗传咨询提供依据。     

200例男性不育患者的Y染色体微缺失检测

目的探讨男性不育患者与Y染色体微缺失之间的关系。方法利用15个Y染色体特异序列标签位点,以多重PCR法检测男性不育患者的Y染色体微缺失情况。结果 200例男性不育患者中共检出Y染色体微缺失7例,缺失率为3.5%。其中单纯A;ZFc缺失2例,缺失率为1%(2/200);A;ZFb缺失率为3例,缺失率为1.5%(3/200);单纯A;ZFa缺失2例,缺失率为1%(2/200),尚未发现联合缺失或大片段缺失患者。精液正常者(对照组)30例未发现Y染色体微缺失。结论 Y染色体微缺失是造成男性不育的常见病因之一。     

A deletion of a novel heat shock gene on the Y chromosome associated with azoospermia

Deletions of the Y chromosome are a significant cause of spermatogenic failure. Three major deletion intervals have been defined and termed AZFa, AZFb and AZFc. Here, we report an unusual case of a proximal AZFb deletion that includes the Y chromosome palindromic sequence P4 and a novel heat shock factor (HSFY). This deletion neither include the genes EIF1AY, RPS4Y2 nor copies of the RBMY1 genes. The individual presented with idiopathic azoospermia. We propose that deletions of the testis-specific HSFY gene family may be a cause of unexplained cases of idiopathic male infertility. This deletion would not have been detected using current protocols for Y chromosome microdeletion screens, therefore we recommend that current screening protocols be extended to include this region and other palindrome sequences that contain genes expressed specifically in the testis.     

男子不育症相关的Y染色体基因组学

由于Y染色体存在性别决定基因和精子发生相关基因,男子不育相关的Y染色体基因组学逐步形成,对男子不育症有了全新的诠释。研究发现:缺乏基因重组的Y染色体不但不会逐渐丢失其重要基因,更不会逐渐消亡,而且也处于不断进化中;人类Y染色体有独特的短串重复序列-微卫星DNA和中度Alu家族重复序列,可能与男子不育症的发生有关;Y染色体上约有107个基因列在基因库,在MSY区域约有156个转录单位,其中78个编码蛋白质有27个蛋白质家族已被确认,11个蛋白质仅在睾丸组织中表达,与调节精子的发生相关;Y染色体所特有的基因不但调节着睾丸的生精功能,可能对前列腺、大脑等人体组织器官也有重要作用。     

人Y染色体类热休克蛋白因子编码特征和男性生精障碍

精子生成障碍是男性不育的主要原因之一，而无精症和少精症在男性不育症患者中，90％是由于生精功能障碍引起，其中特发性生精障碍占60％。近年来通过人类基因组计划的实施，发现不少Y染色体上诱发不育症的候选基因，包括类热休克蛋白因子HSFY、LW-1和mHSFYL。本文通过HSFY、LW-1和mHSFYL的编码特征，阐述它们在精子生成过程中的作用和诱发生精障碍、导致无精症和少精症的遗传学机理。     

DAZ gene copies: evidence of Y chromosome evolution

The DAZ gene, a contributing factor in infertility, lies on the human Y chromosome's AZFc region, whose deletion is a common cause of spermatogenic failure. Y chromosome binary polymorphisms on the non-recombining Y (NRY) region, believed to be a single occurrence on an evolutionary scale, were typed in a sample of fertile and infertile men with known DAZ backgrounds. The Y single-nucleotide polymorphisms (Y-SNPs) with low mutation rates are currently well characterized and permit the construction of a unique phylogeny of haplogroups. DAZ haplotypes were defined using single-nucleotide variant (SNV)/sequence tagged-site (STS) markers to distinguish between the four copies of the gene. The variation of 10 Y chromosome short tandem repeat (STRs) was used to determine the coalescence age of DAZ haplotypes in a comparable time frame similar to that of SNP haplogroups. An association between DAZ haplotypes and Y chromosome haplogroups was found, and our data show that the DAZ gene is not under selective constraints and its evolution depends only on the mutation rate. The same variants were common to fertile and infertile men, although partial DAZ deletions occurred only in infertile men, suggesting that those should only be used as a tool for infertility diagnosis when analysed in combination with haplogroup determinations.     

Men with infertility caused by AZFc deletion can produce sons by intracytoplasmic sperm injection, but are likely to transmit the deletion and infertility.

Deletion of the AZFc region of the Y chromosome is the most frequent molecularly defined cause of spermatogenic failure. We report three unrelated men in whom azoospermia or severe oligozoospermia was caused by de-novo AZFc deletions, and who produced sons by intracytoplasmic sperm injection (ICSI). We employed polymerase chain reaction (PCR) assays to examine the Y chromosomes of their four infant sons. All four sons were found to have inherited the Y chromosome deletions. Such sons are likely to be infertile as adults. This likelihood should be taken into account when counselling couples considering ICSI to circumvent infertility due to severe oligozoospermia or non-obstructive azoospermia.     

The association of Y chromosome haplogroups with spermatogenic failure in the Han Chinese

A significant proportion of male infertility is accompanied by an abnormal semen analysis, azoospermia or severe oligozoospermia, which is generally assumed to be the result of spermatogenic failure. The genetic contribution in the process of spermatogenesis, particularly the role of the Y chromosome in determination of semen quality, is still obscure. In order to explore the relationship between Y chromosome haplogroup and spermatogenic failure, we collected 285 idiopathic infertile males with azoo-/oligozoospermia and 515 fertile men, adopted 12 binary markers and recruited the subjects (cases and controls) in the same region to test whether there is a possible susceptibility of certain Y haplogroups to spermatogenic failure in the Han Chinese population. The results indicated that the prevalences of hg K* in the control and the case population were 0.78% (4/515) and 2.80% (8/285), respectively. The difference between the frequencies of the hg K* in the infertile males and the normal control population was significant [odds ratio (OR) = 3.69; 95% confidence interval (CI) = 1.10–12.36] (P = 0.028). However, in the other haplogroups no significant differences were found. In conclusion, Y haplogroup-K* might bear a risk factor of male infertility, and the individuals in the haplogroup need to be further examined. Chuncheng Lu and Feng Zhang contributed equally to this work.     

Transmission of male infertility to future generations: lessons from the Y chromosome

The introduction of ICSI and testicular sperm extraction (TESE) has allowed many infertile men to father children. The biggest concern about the wide use of these techniques is the health of the resulting offspring, in particular their fertility status. If the spermatogenic defect is genetic in origin, there is potential risk of transmitting this defect to future offspring. The most frequently documented genetic cause of male infertility is a Y chromosome deletion. The Y chromosome has acquired a large number of testis-specific genes during recent evolution, and deletions causing infertility take out a number of these genes. These deletions have been shown to be transmitted to 100% of male offspring. Also, absence of an aberration on the Y chromosome does not rule out a genetic cause of the infertility phenotype, as there are many other genes involved in spermatogenesis elsewhere in the genome, and current mapping techniques--especially on the Y chromosome--can miss many aberrations. More detailed studies of these spermatogenesis genes, which are now possible because of more precise sequence-based mapping, will lead to improved understanding of the genetic basis of male infertility and enable proper counselling of patients undergoing ICSI in the future.     

No AZF deletion in 160 patients with testicular germ cell neoplasia

Testicular germ cell cancer is aetiologically linked to genital malformations and male infertility and is most probably caused by a disruption of embryonic programming and gonadal development during fetal life. In some cases, germ cell neoplasia is associated with a relative reduction of Y chromosomal material (e.g. 45,X/46,XY) or other abnormalities of the Y chromosome. The euchromatic long arm of the human Y chromosome (Yq11) contains three azoospermia factors (AZFa, AZFb, AZFc) functionally important in human spermatogenesis. Microdeletions encompassing one of these three AZF loci result in the deletion of multiple genes normally expressed in testis tissue and are associated with spermatogenic failure. The aim of our study was to investigate whether AZF microdeletions, in addition to causing infertility, predispose also to germ cell neoplasia, since subjects with poor spermatogenesis have an increased risk of testicular cancer. We screened for putative deletions of AZF loci on the Y chromosome in DNA isolated from white blood cells of 160 Danish patients with testicular germ cell neoplasia. Interestingly, although AZF microdeletions are found frequently in patients with idiopathic infertility, in all cases studied of testicular germ cell cancer the Yq region was found to be intact. We conclude that the molecular aetiology of testicular germ cell neoplasia of the young adult type most likely does not involve the same pathways as male infertility caused by AZF deletions. Malignant transformation of germ cells is thus caused by the dysfunction of some other genes that still need to be identified.