无精和严重少精子症患者Y染色体的微缺失

目的 检测我国无精和严重少精子症患者Y染色体微缺失的发生情况和位点,及其与睾丸病理学类型的关系.方法 取584例无精子症和80例严重少精子症患者精液中细胞或外周血白细胞,裂解提取DNA,用4组多重聚合酶链反应检测分布于AZFa、AZFb、AZFc区,包括欧洲男科学会和欧洲分子遗传学质量控制体系推荐的6个位点在内的共15个序列标签位点(sequence tagged site,SIS)的缺失.对部分有Y染色体微缺失患者进行睾丸细针抽吸活检,检查睾丸病理学类型.结果 584例无精子症患者中,共有66例(11.3%)发生Y染色体微缺失,各区发生率构成比由高到低依次为:AZFc区48例(72.7%),AZFb+c区9例(13.6%),AZFa+b+c区4例(6.1%),AZFb区3例(4.5%),A2Fa区2例(3.0%).80例严重少精子症患者共有10例发生Y染色体微缺失(12.5%),均为AZFc区缺失.AZFc区缺失患者(19例)睾丸病理学类型多样化;AZFb+c区或AZFa+b+c区缺失患者(7例)睾丸病理学类型为唯支持细胞综合征或生精阻滞于精原细胞.结论 Y染色体微缺失在我国的发生情况与其他国家大多数报道基本一致,跨区大缺失对精子发生造成严重影响.     

Y chromosome microdeletions in Tunisian infertile males

AIM: To determine frequency of Y microdeletions in azoospermic and oligospermic Tunisian infertile males. METHODS: A Sample of 146 Tunisian infertile males with a low sperm count (<5 x 10(6) sperms per mililiter) and normal karyotype was screened for Y chromosome microdeletions. 76 men were azoospermic and 70 men were oligospermic. Genomic DNA was isolated from blood and multiplex PCR was carried out with a set of 20 AZFa, AZFb and AZFc STS markers to detect the microdeletions as recommended by the European Academy of Andrology. RESULTS: In 10/146 (6.85%) subjects AZF deletions were observed. Of these ten males with microdeletions, 9/10 subjects were azoospermic (90%), 1/10 was oligospermic (10%). Frequency of microdeletions in azoospermic men was 9/76 (11.84%). None of the patients showed isolated microdeletion in the AZFa region, but one azoospermic man had deletion in the AZFb region. Eight azoospermic patients and one oligospremic man have AZFc microdeletions. AZFc and AZFb were deleted in three azoospermic patients. AZFc, AZFb and AZFa were deleted in three azoospermic patients We estimate the sensitivity of the test comprising six STS in our sample to be 90%. CONCLUSION: The incidence of Yq microdeletions in the study population of infertile Tunisian men falls within the range published in other countries. We suggest to analyze 9STS in the first step to detect efficiently Y microdeletions in our population.     

AZF and DAZ gene copy-specific deletion analysis in maturation arrest and Sertoli cell-only syndrome

Deletions of the AZFc region in Yq11.2, which include the DAZ gene family, are responsible for most cases of male infertility and were associated with severe oligozoospermia and also with a variable testicular pathology. To uncover the functional contribution of DAZ to human spermatogenesis, a DAZ gene copy-specific deletion analysis was previously established and showed that DAZ1/DAZ2 deletions associate with oligozoospermia. In this study we applied the same screening method to 50 control fertile males and 91 non-obstructive azoospermic males, 39 with Sertoli cell-only syndrome (SCOS) and 52 with meiotic arrest (MA). Samples were also screened with 24 sequence-tagged sites to the different AZF regions, including 114 control fertile males. After biopsy (testicular sperm extraction, TESE), residual spermiogenesis was found in 57.7% MA and 30.8% SCOS cases (incomplete syndromes). DAZ1/DAZ2 deletions were associated with the testicular phenotype of residual spermiogenesis as they were only found in two patients (8%) with incomplete MA. Differences between incomplete (23.3%) and complete (4.5%) MA cases regarding AZFc and DAZ1/DAZ2 deletion frequencies, and between incomplete (58.3%) and complete (11.1%) SCOS cases for AZFc deletions, suggest that incomplete syndromes might represent an aggravation of the oligozoospermic phenotype. As successful TESE was achieved in 87.5% of MA cases with AZFc and DAZ1/DAZ2 deletions and in 58.3% of SCOS cases with AZFc deletions, the present results also suggest that these molecular markers might be used for the establishment of a prognosis before TESE.     

Y染色体微缺失35例患者临床表型分析

目的分析35例Y染色体微缺失患者临床表型。方法按照WHO标准进行检查和精液分析,证实为非梗阻性无精子症或严重少精子症（〈1×10^6／mL）367例,然后应用改良多重多聚酶链反应（multiplex—PCR）,对367例不育患者进行Y染色体微缺失分子学诊断。将微缺失患者分为两组：严重少精子组和无精子组。再按缺失类型将无精子组分为两个亚组：单纯AZFc缺失组和其它类型缺失组。采集以下临床资料进行分析：结婚年龄、不育史、精液分析、睾丸体积、附睾睾丸穿刺情况、染色体核型分析以及性激素检测。结果367例中发现AZF微缺失35例（9．54％）,其中AZFa、AZFb微缺失各1例（2．86％）,AZFc微缺失29例（82．86％）,AZFb＋c微缺失2倒（5．71％）,AZFa＋b＋c微缺失2例（5．71％）。严重少精子患者14例,缺失类型均为AZFc;无精子症患者21例,其中对12例无精子症患者行睾丸穿刺活检,2例AZFc微缺失患者发现精子。其中未发现输精管缺如患者。染色体核型分析2例AZFc微缺失患者发现异常,其余均为46,XY。严重少精子组与无精子组患者年龄、不育年限、黄体生成素、雄激素及出生时父亲年龄无统计学差异,卵泡刺激素有统计学差异。结论 临床表型、染色体核型正常的严重少弱精子或无精子症患者可存在Y染色体微缺失,其发生率约为10％,最常见的类型为AZFc微缺失。单纯AZFc缺失对精子生成的影响比其他类型缺失较小,无精子症AZFc缺失者行睾丸穿刺活检有可能发现可用精子,AZFa、AZFb或AZFa＋b＋c缺失者基本不可能有精子,临床上无睾丸活检的价值。     

AZF deletions and Y chromosomal haplogroups: history and update based on sequence

AZF deletions are genomic deletions in the euchromatic part of the long arm of the human Y chromosome (Yq11) associated with azoospermia or severe oligozoospermia. Consequently, it can be assumed that these deletions remove Y chromosomal genes required for spermatogenesis. However, these 'classical' or 'complete' AZF deletions, AZFa, AZFb and AZFc, represent only a subset of rearrangements in Yq11. With the benefit of the Y chromosome sequence, more rearrangements (deletions, duplications, inversions) inside and outside the classical AZF deletion intervals have been elucidated and intra-chromosomal non-allelic homologous recombinations (NAHRs) of repetitive sequence blocks have been identified as their major cause. These include duplications in AZFa, AZFb and AZFc and the partial AZFb and AZFc deletions of which some were summarized under the pseudonym 'gr/gr' deletions. At least some of these rearrangements are associated with distinct Y chromosomal haplogroups and are present with similar frequencies in fertile and infertile men. This suggests a functional redundancy of the AZFb/AZFc multi-copy genes. Alternatively, the functional contribution(s) of these genes to human spermatogenesis might be different in men of different Y haplogroups. That raises the question whether, the frequency of Y haplogroups with different AZF gene contents in distinct human populations leads to a male fertility status that varies between populations or whether, the presence of the multiple Y haplogroups implies a balancing selection via genomic deletion/amplification mechanisms.     

AZF缺失患者Y染色体断裂点定位分析

目的 分析导致无精子因子区域(azoospermia factor,AZF)缺失的Y染色体断裂的特点.方法 在272例无精子症、240例严重少精子症患者进行Y染色体AZF微缺失筛查基础上,对筛查发现大片段缺失的49例患者,选择AZFa、AZFb、AZFc区23个序列标签位点(sequence tagged site,STS),对断裂点进行定位分析.颖有无精子症缺失基因家族(deletedin azoospermia,DAZ)、基因部分拷贝缺失病例进行单核苷酸多态性(single nuecleotide varians,SNV)缺失分析以确定DAZ基因的拷贝数.结果 6例AZFb+C缺失患者,1例为sY98/sY1206缺失,4例为P5/P1远端重组,1例为P4/P1远端重组.3例筛查发现AZFb区缺失患者,1例为P5/P3缺失,2例为P5/P1近端重组,伴有DAZ1、DAZ2拷贝缺失.40例AZFc区全缺失患者,均为b2/b4同源重组.部份AZFb、AZFb+c缺失患者,睾丸穿刺活检发现精子生成减少或精子成熟障碍.结论 对Y染色体AZF大片段缺失断裂点的大致定位有利于判断缺失发生机制,进而分析丢失的生精相关基因拷贝性质与数量,以评价其与生精障碍表型之间的关联.     

Prognostic value of Y deletion analysis: what is the clinical prognostic value of Y chromosome microdeletion analysis?

In many centres, Y chromosome deletion analysis is still not performed routinely and if so, the results are used for genetic counselling but are not considered as having a useful prognostic value. The type of deletion (AZFa, b or c) has been proposed as a potential prognostic factor for sperm retrieval in men undergoing TESE. AZFc deletions and partial AZFb deletions are associated with sperm retrieval in approximately 50% of cases while in the case of a patient with complete AZFb deletion the probability of finding mature spermatozoa is virtually nil. Therefore the extent and position of a Y microdeletion is important (complete or partial). The prognostic value of Y chromosome deletion analysis in cases of oligozoospermia is important when one considers the progressive decrease of sperm number over time in men with AZFc deletions. Cryo-conservation of spermatozoa in these cases could avoid invasive techniques, such as TESE/ICSI, in the future. Male offspring that are conceived by ICSI or IVF techniques from father with oligozoospermia or azoospermia would also benefit from knowledge of their Y status, since the identification of the genetic defect will render future medical or surgical therapies unnecessary. Y microdeletion screening is therefore important, not only to define the aetiology of spermatogenic failure, but also because it gives precious information for a more appropriate clinical management of both the infertile male and his future male child.     

COMMENTS

Human spermatogenesis is regulated by a network of genes located on autosomes and on sex chromosomes, but especially on the Y chromosome. Most results concerning the germ cell function of the Y genes were obtained by genomic breakpoint mapping studies of the Y chromosome of infertile patients. Although this approach has the benefit of focussing on those Y regions that contain most likely the Y genes of functional importance, its major drawback is the fact that fertile control samples were often missing. In fertile men, molecular and cytogenetic analyses of the Y chromosome has revealed highly polymorphic chromatin domains especially in the distal euchromatic part (Yq11.23) and in the heterochromatic part (Yq12) of the long arm. In sterile patients cytogenetic analyses mapped microscopically visible Y deletions and rearrangements in the same polymorphic Y regions. The presence of a Y chromosomal spermatogenesis locus was postulated to be located in Yq11.23 and designated as AZoospermia Factor (ZF). More recently, molecular deletion mapping in Yq11 has revealed a series of microdeletions that could be mapped to one of three different AZF loci: AZFa in proximal Yq11 (Yq11.21), AZFb and AZFc in two non‐overlapping Y‐regions in distal Yq11 (Yq11.23). This view was supported by the observation that AZFa and AZFb microdeletions were associated with a specific pathology in the patients' testis tissue. Only AZFc deletions were associated with a variable testicular pathology and in rare cases AZFc deletions were even found inherited from father to son. However, AZFc deletions were found with a frequency of 10–20% only in infertile men and most of them were proved to be “de novo”, i.e. the AZFc deletion was restricted to the patient's Y chromosome. Based mainly on positional cloning experiments of testis cDNA clones and on the Y chromosomal sequence now published in GenBank, a first blueprint for the putative gene content of the AZFc locus can now be given and the gene location compared to the polymorphic DNA domains. This artwork of repetitive sequence blocks called AZFc amplicons raised the question whether the AZFc chromatin is still part of the heterochromatic domain of the Y long arm well known for its polymorphic extensions or is decondensed and part of the Yq11.23 euchromatin? We discuss also the polymorphic DAZ gene family and disclose putative origins of its molecular heterogeneity in fertile and infertile men recently identified by the analyses of Single Nucleotide Variants (SNVs) in this AZFc gene locus.     

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。     

Polymorphic DAZ gene family in polymorphic structure of AZFc locus: Artwork or functional for human spermatogenesis?

Human spermatogenesis is regulated by a network of genes located on autosomes and on sex chromosomes, but especially on the Y chromosome. Most results concerning the germ cell function of the Y genes were obtained by genomic breakpoint mapping studies of the Y chromosome of infertile patients. Although this approach has the benefit of focussing on those Y regions that contain most likely the Y genes of functional importance, its major drawback is the fact that fertile control samples were often missing. In fertile men, molecular and cytogenetic analyses of the Y chromosome has revealed highly polymorphic chromatin domains especially in the distal euchromatic part (Yq11.23) and in the heterochromatic part (Yq12) of the long arm. In sterile patients cytogenetic analyses mapped microscopically visible Y deletions and rearrangements in the same polymorphic Y regions. The presence of a Y chromosomal spermatogenesis locus was postulated to be located in Yq11.23 and designated as AZoospermia Factor (ZF). More recently, molecular deletion mapping in Yq11 has revealed a series of microdeletions that could be mapped to one of three different AZF loci: AZFa in proximal Yq11 (Yq11.21), AZFb and AZFc in two non-overlapping Y-regions in distal Yq11 (Yq11.23). This view was supported by the observation that AZFa and AZFb microdeletions were associated with a specific pathology in the patients' testis tissue. Only AZFc deletions were associated with a variable testicular pathology and in rare cases AZFc deletions were even found inherited from father to son. However, AZFc deletions were found with a frequency of 10-20% only in infertile men and most of them were proved to be "de novo", i.e. the AZFc deletion was restricted to the patient's Y chromosome. Based mainly on positional cloning experiments of testis cDNA clones and on the Y chromosomal sequence now published in GenBank, a first blueprint for the putative gene content of the AZFc locus can now be given and the gene location compared to the polymorphic DNA domains. This artwork of repetitive sequence blocks called AZFc amplicons raised the question whether the AZFc chromatin is still part of the heterochromatic domain of the Y long arm well known for its polymorphic extensions or is decondensed and part of the Yq11.23 euchromatin? We discuss also the polymorphic DAZ gene family and disclose putative origins of its molecular heterogeneity in fertile and infertile men recently identified by the analyses of Single Nucleotide Variants (SNVs) in this AZFc gene locus.     

Validation of a simple Yq deletion screening programme in an ICSI candidate population

This study reports on the validation of a diagnostic screening programme for Yq deletions in a population of infertile men. First, an unselected group of 402 intracytoplasmic sperm injection (ICSI) candidate patients was screened prospectively by means of three polymerase chain reactions (PCR) each with one marker in the region AZFa, AZFb or AZFc. With this screening strategy, eight males (2.2%) were found to carry a deletion in Yq11. Secondly, a subgroup of males were further analysed by multiplex PCR with 27 sequence-tagged sites. In this group of 229 cytogenetically normal males with azoospermia, cryptozoospermia or extreme oligozoospermia, including some patients with varicocele or a history of cryptorchidism, only one additional microdeleted patient was found with the multiplex PCR. Hence we obtained a frequency of 2.2% (9/402) or 4% (9/229) in the unselected and selected patient groups respectively. We conclude that in a diagnostic programme for Yq deletions in ICSI candidates it might be sufficient to use only four markers representing the three AZF regions and a more distal region in AZFc. In this way, it is possible to detect most, if not all, Yq deletions which might be the causal factor in the patient's infertility.     

特发性无精子症及少弱精子症患者Y染色体AZF微缺失筛查分析

目的探讨特发性无精子症及少弱精子症不育男性与Y染色体AZF微缺失的关系.方法用双重PCR技术对63例患者(无精于症41例,少弱精子症14例,严重少精子症8例)进行Y染色体AZFa、AZFb、AZFc、SRY的微缺失筛查.同时对26例无精于症患者行睾丸活检、组织学评估.结果63例中AZF微缺失7例,缺失率为11.1%.其中无精子症5例,严重少精子症2例.AZFc缺失4例,AZFb缺失2例,AZFb AZFc缺失1例,未发现AZFa区缺失.63例及对照组30例SRY基因扩增均阳性.26例无精子症患者行睾丸活检、组织学检查,无1例精子发生正常.结论Y染色体微缺失,特别是AZFc区DAZ基因的微缺失,是引起无精子和严重少弱精子等生精障碍而致男性不育较为重要的遗传学因素.     

男性不育患者Y染色体的AZF基因微缺失分析

目的探索男性不育患者Y染色体AZF基因微缺失的发生情况，为男性不育的临床诊断和治疗提供科学依据。方法应用PCR方法对36例无精或严重少精患者AZF基因的SY84、SY127和SY254进行检测分析。结果在36例患者中发现16例发生AZF基因的微缺失，均为三个基因区段不同组合的缺失。其中涉及AZFa或AZFb缺失的各8例，涉及AZFc缺失的有14例。结论AZF基因的微缺失与某些男性不育密切相关。AZFc缺失可能是男性不育中无精子、严重少精子的主要病因之一。     

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.     

甘肃部分地区373例男性不育患者Y染色体AZF微缺失基因诊断的研究

目的研究甘肃地区男性不育患者Y染色体AZF区域微缺失的频率、分布情况方法采用多重PCR技术,对甘肃地区373例男性不育症患者进行Y染色体AZFa,AZFb,AZFc三个区域6个STS位点的微缺失检测。结果 373例男性不育患者中,42例发生了STS位点缺失,缺失率11.3%。其中无精子症因子AZFa(SY86,SY84)区未见缺失;AZFb(SY127,SY134)区缺失4例(9.52%);AZFc(SY254,SY255)区缺失32例(76.2%);AZFb+c区缺失5例(11.9%);AZFa+b+c缺失1例(2.38%)。结论甘肃部分地区AZF区域微缺失的频率、分布与国内其他报道一致,但是在本研究中未检测到AZFa区缺失患者。     

Y chromosome deletions in azoospermic and severely oligozoospermic men undergoing intracytoplasmic sperm injection after testicular sperm extraction

Y chromosome deletions encompassing the AZFc region have been reported in 13% of azoospermic men and 7% of severely oligozoospermic men. We examined the impact of these Y deletions on the severity of testicular defects in 51 azoospermic men undergoing intracytoplasmic sperm injection (ICSI) after testicular sperm extraction (TESE) and 30 men with severe oligozoospermia undergoing ICSI after ejaculation of spermatozoa. In addition, five azoospermic patients shown previously to have Y chromosome deletions underwent histological evaluation of their previously obtained testis biopsy specimens. A further 27 azoospermic men underwent TESE-ICSI, but not Y chromosome DNA testing. Ten of 51 azoospermic men (20%) who underwent TESE-ICSI and Y-DNA testing were found to be deleted for portions of the Y chromosome AZFc region. Of these 10, five had spermatozoa retrievable from the testis, and in two cases the wives became pregnant. Of the 41 azoospermic men with no Y chromosome deletion, 22 (54%) had spermatozoa retrievable from the testis, and in 12 cases (29%) the wives became pregnant. Four of 30 (13%) severely oligozoospermic patients were found to be deleted for AZFc and in three (75%) of these pregnancy was achieved. The other 26 severely oligozoospermic couples who had no AZFc deletions underwent ICSI, and 12 (46%) have an ongoing or delivered pregnancy. The embryo implantation rate was not significantly different for azoospermic (22%), oligozoospermic (16%), Y-deleted (14%) or Y-intact (18%) men. Of the total of 19 infertile men who had Y chromosome deletions, 14 had deletions within Y chromosome intervals 6D-6F, in the AZFc region. Twelve of those 14 had some spermatozoa (however few in number) in the ejaculate or testis. Five of the Y-deleted men had deletions that extended more proximally on the Y chromosome, and in none of these could any spermatozoa be observed in either ejaculate or testis. These results support the concept that, in azoospermic or oligozoospermic men with Y chromosome deletions limited to intervals 6D-6F (AZFc), there are generally very small numbers of testicular or ejaculated spermatozoa. Larger Y deletions, including and extending beyond the AZFc region and encompassing more Y genes, tend to be associated with a total absence of testicular spermatozoa. In those cases where spermatozoa were retrieved, the presence of Y deletions had no obvious impact on fertilization or pregnancy rate.      

Human chromosome deletions in Yq11, AZF candidate genes and male infertility: history and update

Human chromosome deletions in Yq11 seem to occur frequently as de novo mutation events in men with idiopathic azoospermia or severe oligozoospermia. However, the molecular extensions of these deletions are variable. They can be large and therefore visible under the microscope or small, not visible under the microscope, and containing the deletion of one or more DNA loci recently mapped in an apparently consecutive order along the Yq11 chromosome region. The results of 20 extensive microdeletion screening programmes have now corroborated the prevalence of the deletion of three non-overlapping DNA regions in proximal, middle and distal Yq11, which were designated earlier as AZFa, AZFb and AZFc. Deletions of single DNA loci were also reported, but as de novo and as polymorphic mutation events. Their clinical significance with regard to the men's infertility should therefore initially be handled with caution. Multiple Y genes expressed in human testis have now been mapped to each AZF region. At least one of them should be functional in human spermatogenesis and, if mutated, cause azoospermia. However, gene-specific mutations leading to the azoospermia phenotype have not yet been found for any of these AZF candidate genes. This might raise the question as to whether an AZF gene really exists in Yq11 or if the azoospermia phenotypes are only observed after deletion of a complete AZF region, after deletion of its complete gene content.      

不育男性的AZF检测与Y染色体缺失的对照分析

目的探讨精子发生障碍的男性不育患者AZF缺失与Y染色体缺失的临床意义。方法对616例非阻塞性无精子症或少精子症患者进行AZF的检测,同时观察G显带Y染色体的形态。结果从616例患者中检测出48例患者分别为AZFa、AZFb、AZFc或AZFb+AZFc的微缺失,但显微镜下观察不到Y染色体形态改变。另外4例患者经AZF检测,2例为AZFc+sY160缺失,1例为AZFb+AZFc+sY160缺失,1例为AZFa+AZFb+AZFc+sY160缺失,显微镜下发现Yq部分或完全缺失。25例已育男性的G-显带的Y染色体和AZF也进行对照检测,均未发现AZF的缺失,但其中1例核型分析显示Y染色体长臂部分缺失,但PCR检测仅缺失sY160,即Yq12的缺失。结论Yq11.23上7Mb的缺失在细胞水平不能分辨。q11.23+q12的缺失或仅有Yq12的缺失的Y染色体显微镜下不能区分,但后者不是精子发生障碍的病因。对男性不育精子发生障碍患者,要结合细胞遗传学和AZF分子检测综合判断。     

Prognostic value of Y deletion analysis. The role of current methods

Y chromosome microdeletions represent the most frequent genetic alteration in azoospermic and severely oligozoospermic men, and screening for microdeletions in AZFa, b and c are routinely performed in the major andrology and infertility centres. Since patients with Y microdeletions often require intracytoplasmic sperm injection (ICSI), the question of whether the type of the microdeletion present could have prognostic value for the presence of spermatozoa in the ejaculate or in the testes [by testicular sperm extraction (TESE)] is an interesting one. The review of the literature on this topic showed that there is still no clear genotype--phenotype relationship, i.e. similar testicular alterations may be caused by different types of microdeletions, and apparently identical microdeletions may be associated with diverse tubular damage. Even in azoospermic men, the localization of the microdeletion cannot be used as a valid prognostic parameter before TESE--ICSI to identify patients with spermatozoa in their testes. The only finding with absolute negative prognostic value is the presence of complete AZFa--c deletions, which are invariably associated with an absence of spermatozoa. Microdeletions in AZFa or AZFb seem to have promising prognostic value, but more data and gene-specific deletions have to be provided to draw clear conclusions. The absence of a clear genotype--phenotype relationship, and therefore of a prognostic value of Y deletion analysis, is probably due to the current methods used for the screening of the microdeletions. In fact, to date most centres do not use gene-specific markers but instead use anonymous primers that contribute little information to the pathogenic role of the microdeletions.