男性不育中Y染色体微缺失的研究进展

近年来对男性不育的遗传学因素的广泛研究显示Y染色体微缺失是导致不同程度生精障碍从而引起男性不育的第二大遗传学病因。无精子症因子区(AZF区)由近至远包含3个不同的亚区:AZFa、AZFb和AZFc,不同缺失类型的表型不同。目前常采用PCR法进行Y染色体微缺失的检测,其缺点是准确度低、特异性差、耗时。而基因芯片技术虽能克服上述缺点,但目前成本过高。通过检测能预测患者男性后代的遗传风险,有助于患者选择辅助治疗的方式。虽然Y染色体微缺失的严重不育患者能通过辅助生殖技术成功获得后代,但有可能将遗传缺陷传给男性后代,使之获得相同的Yq微缺失和不育。     

Y染色体微缺失与辅助生殖技术关系的研究进展

Y染色体是男性特有的染色体,其长臂上的无精子因子(AZF)区域具与男性不育密切相关的基因,目前将该区域分为AZFa、AZFb、AZFc和AZFd4个区域。AZF缺失是导致男性不育的重要因素之一,可以通过辅助生殖技术(ART)遗传给下一代引起不育。研究Y染色体微缺失分类与表型关系,可以为临床治疗各种男性不育症提供分子或细胞水平的依据。Y染色体微缺失发生频率存在种族差异性;目前Y染色体微缺失的检测方法仍然以多重PCR为主;对于ICSI助孕的男性后代是否会出现新发Y染色体微缺失仍然存在争论。     

AZF微缺失与男性不育

Y染色体是男性特有的染色体,其上含有与精子发生相关的基因。越来越多研究证实AZF区基因微缺失与男性不育密切相关,并且可能以正常生殖或辅助生殖方式遗传给后代引起不育。本文从Y染色体微缺失基因类型、Y染色体缺失机制及Y染色体微缺失的临床意义三个方面综述。     

Y染色体微缺失对卵胞质内单精子注射胚胎情况和临床结局的影响

目的:探讨Y染色体微缺失对卵胞质内单精子注射(ICSI)胚胎形成情况和临床结局的影响。方法:收集22例Y染色体微缺失患者进行的27个ICSI治疗周期(研究组)的胚胎和临床结局资料,另收集同期88例严重少精子症或无精子症非Y染色体微缺失患者的101个ICSI治疗周期(对照组)的相应资料进行回顾性分析;同时比较不同Y染色体微缺失类型患者进行ICSI的胚胎资料和临床结局。结果:研究组和对照组的受精率分别为84.91%与86.30%,卵裂率分别为95.45%与96.79%,优质胚胎率分别为49.35%与45.03%,新鲜周期移植优质胚胎率分别为80.36%与84.80%,临床妊娠率分别为65.22%与60.40%,胚胎着床率分别为41.07%与33.60%,早期流产率分别为0.00%与4.92%,活产率分别为56.52%与55.45%,男婴比例分别为56.25%与47.83%。各观察指标组间均无统计学差异(P>0.05)。AZFb区部分缺失组2个新鲜胚胎移植周期中有1例获得生化妊娠,但后转阴性;d区部分缺失组及d区和c区部分缺失组各1次新鲜胚胎移植周期且均未获得妊娠;d区部分缺失加c区全部缺失组19个新鲜胚胎移植周期15例获得妊娠且无一例发生流产。结论:Y染色体微缺失对ICSI治疗周期形成的胚胎情况和妊娠结局无显著性影响,但AZFd区部分缺失加c区全部缺失患者配偶临床妊娠机会高于其他类型Y染色体微缺失患者,AZFb区部分缺失病例配偶有妊娠丢失发生。     

精子发生障碍患者Y染色体微缺失分子诊断

目的:通过建立的Y染色体微缺失筛查方法了解生精障碍与Y染色体微缺失的关系。方法:同时采用多重PCR-凝胶电泳技术和多重PCR-液态芯片技术对原发性无精症、少精症患者和精液常规正常男性对照进行Y染色体微缺失筛查。结果:42例无精症、少精症患者中,6例有AZF区域STS位点或基因的缺失,总缺失率为14.3%,AZFc/DAZ区发生微缺失的频率较高,AZFa区发生微缺失的频率较低。结论:本研究建立的Y染色体微缺失多重PCR-MASA检测系统具有相对高通量、简便、快速、特异性强、敏感性高等特点;染色体微缺失是导致男性精子发生障碍的重要原因之一,AZF的候选基因在精子发生过程中可能起重要作用。     

516例无精症Y染色体微缺失及细胞遗传学分析

目的 探讨Y染色体微缺失和细胞遗传学分析在无精症中的相关性.方法 对2015年3月至2019年12月来广东省妇幼保健院就诊的诊断为无精症的患者进行外周血染色体G显带核型分析,运用多重定量荧光聚合酶链反应(quantitative fluorescent PCR,QF-PCR)技术检测Y染色体上的无精因子(azoospe...     

无精症、少精症患者中AZF缺失的检测

目的:探讨AZF缺失与男性无精症、少精症之间的关系。方法:采用多重PCR方法,对84例汉族无精症和少精症患者的AZF区4个STS位点:AZFa亚区的sY86、AZFb亚区的sY127、AZFc亚区的sY254和sY255进行了缺失检测。用PCR-SSCP方法对其中的48例作了sY254点突变检测。并对DAZ基因在人不同组织的表达进行了研究。结果:3例无精症患者同时具有位于AZFc亚区中DAZ基因的sY254和sY255位点缺失。48例患者未见sY254有点突变。只在睾丸组织中检测到DAZ基因的表达。结论:部分汉族无精症患者可能与AZFc的缺失有关。     

毛细管电泳用于Y染色体微缺失的研究

目的:探讨毛细管电泳在研究男性不育中特发性无精子症和射出精液严重少精子症与Y染色体无精子因子(azoospermiafactor,AZF)缺失的作用。方法:应用多重PCR技术对4例无精子症和29例严重少精子症患者的外周血细胞中Y染色体AZF所在的11.23区的15个位点进行扩增,分别用琼脂糖凝胶电泳和毛细管电泳分离扩增产物,并以6例正常生育男性和2例女性为对照。结果:毛细管电泳发现4例无精子症中3例发生缺失,29例严重少精子症患者中6例发生缺失。其中6例同为SY254(C)、SY242(C)、SY255(C)、SY239(C)、SY152(D)缺失。6例正常生育男性毛细管电泳未发现Y染色体微缺失,而凝胶电泳有2个条带模糊,难以判断。结论:毛细管电泳可提高AZF检测准确性。Y染色体AZFc/DAZ的缺失可能是引起无精子和严重少精子并造成男性不育的重要原因之一。     

男性不育患者Y染色体多态对卵胞浆内单精子注射妊娠结局的影响

目的:探讨Y染色体多态对卵胞浆内单精子注射(ICSI)治疗结局的影响。方法:因男性严重少、弱精或梗阻性无精拟行ICSI治疗的患者术前行外周血染色体检查,以Y染色体多态者作为研究组(35个移植周期),随机选取同期行ICSI治疗,Y染色体正常者作为对照组(48个移植周期),比较组间行ICSI治疗的各项指标。结果:Y染色体多态性组和对照组的获卵数(12.5±6.4个vs11.8±4.2个)、正常受精数(8.1±4.6个vs9.1±3.3个)、卵裂数(7.9±4.6个vs8.9±3.4个)、优质胚胎数(5.3±3.5个vs5.9±2.9个)、临床妊娠率(48.57%vs56.25%)、流产率(11.76%vs25.93%)、新生儿出生孕周(37.07±2.60周vs38.00±1.02周)、体质量(2.95±0.90kgvs3.22±0.54kg)组间均无统计学差异(P>0.05)。结论:Y染色体多态对于ICSI治疗结局无明显影响。     

Y染色体基因微缺失与男性不育的关系

目的 :探讨男性不育患者尤其是特发性无精子症、严重少精子症及双侧输精管缺如与 Y染色体基因 (无精子因子 ,AZF)微缺失的关系。方法 :对 97例男性不育患者及 2 0例正常男性采用多重聚合酶链反应法进行基因微缺失检测。结果 :36例特发性无精症患者中存在 3例缺失 ,占 8.33% ;1 4例双侧输精管缺如患者存在 2例缺失 ,占 1 4.2 9% ;2 7例严重少精症患者中存在 2例缺失 ,占 7.41 %。2 0例精子数正常的男性不育患者及 2 0例正常男性对照无 AZF缺失。缺失以 AZFa,AZFc区为主 ,AZFb区无缺失。结论 :Y染色体 AZF微缺失可能是导致男性特发性无精症、少精症的原因之一 ,双侧输精管缺如患者也存在 Y染色体的基因微缺失     

Azoospermia factor and male infertility

Recently, work has shown that azoospermia factor (AZF) microdeletions result from homologous recombination between almost identical blocks in this gene region. These microdeletions in the Y chromosome are a common molecular genetic cause of spermatogenetic failure leading to male infertility. After completion of the sequencing of the Y chromosome, the classical definition of AZFa, AZFb, and AZFc was modified to five regions, namely AZFa, P5/proximal-P1, P5/distal-P1, P4/distal-P1, and AZFc, as a result of the determination of Y chromosomal structure. Moreover, partial AZFc deletions have also been reported, resulting from recombination in their sub-ampliconic identical pair sequences. These deletions are also implicated in a possible association with Y chromosome haplogroups. In this review, we address Y chromosomal complexity and the modified categories of the AZF deletions. Recognition of the association of Y deletions with male infertility has implications for the diagnosis, treatment, and genetic counseling of infertile men, in particular candidates for intracytoplasmic sperm injection.     

Y chromosome AZFc microdeletion may not affect the outcomes of ICSI for infertile males with fresh ejaculated sperm

Purpose

To explore whether the presence of a Y chromosome AZFc microdeletion confers any adverse effect on the outcomes of intracytoplasmic sperm injection (ICSI) with fresh ejaculated sperm.

Methods

A total of 143 oligozoospermia patients with Y chromosome AZFc microdeletion in ICSI cycles in a five-year period were studied. Infertile men with normal Y chromosome in ICSI at the same time-frame were used as controls matched to the study group for age of female, female’s body mass index, male’s age, infertility duration and number of oocytes retrieved. Retrospective case–control study was used.

Results

There were no significant differences between groups in clinical outcomes of endometrial thickness, transferred embryos, good embryo rates, implantation rates, biochemical pregnancy rates, clinical pregnancy rates, ectopic pregnancy rates, miscarriage rates, preterm birth rates, the ratio of male and female babies, newborn body height, newborn weight, low birth weight and birth defects (P > 0.05). Patients with Y chromosome AZFc microdeletion had a lower fertilization rate (61.8 % vs. 67.8 %, P < 0.05) and higher cleaved embryo rate (94.0 % vs. 88.1 %, P < 0.05).

Conclusions

ICSI clinical outcomes for oligozoospermic patients with Y chromosome AZFc microdeletion are basically comparable to that of infertile patients with normal Y chromosomes. The results of ICSI were not affected by the AZFc deletion. Preimplantation genetic diagnosis (PGD) before ICSI for Y chromosome AZFc microdeletion may not be a justifiable regular procedure if the couples didn’t care the vertical transmission of Y chromosome deletion.     

Study of Microdeletions in the Y Chromosome of Infertile Men with Idiopathic Oligo- or Azoospermia

Purpose: To determine the relationships between idiopathic oligo- or azoospermia and microdeletions of the Y chromosome.Methods: Eighteen Y-linked sequence-tagged sites (STSs) in AZF (Azoospermia Factor) region were screened by means of multiplex PCR (Polymerase Chain Reaction) in 50 idiopathic infertile men, including 16 patients with azoospermia, 13 severe oligospermia, and 21 oligospermia.Results: Microdeletions in the genomic DNA were observed in 8 of 50 cases, 3 with azoospermia, 1 severe oligospermia, and 4 oligospermia. Total deletion rate was 16.0% (8/50). The deletion regions were concentrated on AZFd and AZFc.Conclusions: Microdeletions of the Y chromosome are an important cause for idiopathic oligo- or azoospermia. Multiplex PCR is a useful technique for detecting the microdeletions. To avoid transmission to their offspring, patients with idiopathic oligo- or azoospermia should be screened for microdeletions of the Y chromosome before ICSI treatment for infertility.     

Detection of Azoospermic Factor Genes in Chinese Men with Azoospermia or Severe Oligozoospermia

Purpose:We investigated the prevalence of deletions in the azoospermic factor (AZF) region of chromosome Yq11 in Chinese men with infertility due to idiopathic azoospermia or severe oligozoospermia. The DAZ gene cluster was also examined for mutations.Methods:Sixty-eight men with azoospermia or severe oligozoospermia taking part in an intracytoplasmic sperm injection program were recruited. Four loci specific for AZFa, AZFb, and AZFc were amplified from genomic DNA via polymerase chain reaction to determine whether deletions were present in the AZF region. Direct DNA sequencing of amplified products was also performed to look for mutations or polymorphism from exon 2 to exon 6 of the DAZ gene cluster.Results:Six (9%) of the 68 patients had AZF deletions. None had mutations in exons 2 to 6 of DAZ.Conclusions:The prevalence of AZF deletions in our study was similar to those in Western reports, as was the lack of DAZ mutations.     

A comparative study of Y chromosome microdeletions in infertile males from two Chinese populations

Purpose : To compare the prevalence and type of Y-microdeletions in Hong Kong and Shanghai men with severe male-factor infertility. Methods : Seven Y-linked sequence tagged site (STS) primers and seven gene-specific primers were screened in 293 infertile males (139 from Hong Kong and 154 from Shanghai) and 161 fertile men (61 from Hong Kong and 100 from Shanghai). Serum FSH, LH, and testosterone levels were also measured in these men. Results : The incidence of Yq microdeletions in nonobstructive azoospermic men from Hong Kong (8.5%) and Shanghai (6%) was similar. Yq microdeletions were observed in severe oligospermic patients (8.5%) from Hong Kong but not from Shanghai. Among the 9 Hong Kong men with Y-microdeletions, 8 had AZFc deletion and one had AZFb deletion. In contrast, 6 of 9 men from Shanghai with Y-microdeletions had AZFb deletion. The incidence of AZFb deletion among Y-microdeleted men was statistically different between the two populations. Two of the men with AZFb deletion also had AZFa and AZFc deletions. Conclusions : Regional variations in the type of Y-microdeletion existed between Hong Kong and Shanghai infertile males.     

Molecular and cytogenetic studies of 101 infertile men with microdeletions of Y chromosome in 1,306 infertile Korean men

Objectives

To determine the prevalence of Y chromosome microdeletions in infertile Korean men with abnormal sperm counts and to assess the clinical features and frequency of chromosomal abnormalities in Korean patients with microdeletions.

Methods

A total of 1,306 infertile men were screened for Y chromosome microdeletions, and 101 of them had microdeletions. These 101 men were then retrospectively studied for cytogenetic evaluation, testicular biopsy and outcomes of IVF and ICSI.

Results

The overall prevalence of Y chromosome microdeletions in infertile men was 7.7 % (101/1,306). Most microdeletions were in the AZFc region (87.1 %), including deletions of AZFbc (24.7 %) and AZFabc (8.9 %). All patients with AZFa, AZFbc and AZFabc deletions had azoospermia, whereas patients with an AZFc deletion usually had low levels of sperm in the ejaculate or in the testis tissues. Chromosomal studies were performed in 99 men with microdeletions, 36 (36.4 %) of whom had chromosomal abnormalities. Among the infertile men with Y chromosome microdeletions in this study, the incidence of chromosomal abnormality was 48.6 % in the azoospermic group and 3.7 % in the oligozoospermic group. Among the 69 patients with microdeletions and available histological results, 100.0 % of the azoospermic group and 85.7 % of the oligozoospermic group had histological abnormalities. The frequency of both chromosomal abnormalities and histological abnormalities was higher in the azoospermic group compared to the oligozoospermic group. Thirty-four ICSI cycles with either testicular (n = 14) or ejaculated spermatozoa (n = 20) were performed in 23 couples with men with AZFc microdeletion. Thirteen clinical pregnancies (39.4 %) were obtained, leading to the birth of 13 babies.

Conclusions

The study results revealed a close relationship between microdeletions and spermatogenesis, although IVF outcome was not significantly affected by the presence of the AZFc microdeletion. Nevertheless, Y chromosome microdeletions have the potential risk of being transmitted from infertile fathers to their offspring by ICSI. Therefore, before using ICSI in infertile patients with severe spermatogenic defects, careful evaluations of chromosomal abnormalities and Y chromosome microdeletions screening should be performed and genetic counseling should be provided before IVF-ET.