精子发生障碍的遗传学研究进展

不孕不育影响着约10%～15%的夫妇,其中男性因素约占一半。精子发生障碍是男性不育的主要病因,主要表现为无精子症或少弱精子症。大量研究已经确定Y染色体及Yq微缺失与男性不育的相关性。X染色体因其在男性仅有单拷贝而在精子生成过程中表达特殊,对精子发生障碍有重要意义。对畸精子症和弱精子症患者的研究表明,位于常染色体的4个基因（SPATA16,PICK1,CATSPER和AURKC）可能与精子发生障碍有关。虽然经全球范围的努力,预期在不久的将来可提供新的基因检测技术来检测精子发生障碍的遗传学原因,但目前可用于精子发生障碍的基因测试仍然有限。     

婴幼儿尘螨严重过敏症的遗传学初步研究

目的 对14例0岁～4岁婴幼儿尘螨严重过敏症进行全外显子组测序，探讨其可能的遗传学致病因素。方法 对14例患儿进行全外显子组测序，对相关变异位点进行Sanger测序验证。通过文献及数据库查找，筛选与过敏性疾病相关的基因集，并在外显子组水平、疾病相关基因集水平比较患者组和对照组的变异负荷。结果 通过对受检者进行遗传病相关基因测序、生物信息学分析、遗传分析(遗传模式包括常染色体显性遗传、常染色体隐性遗传、X/Y连锁)及结合临床表型的综合分析，未检测到与受检者临床表型相关的已知或可能具有临床意义的基因变异。与对照组相比，患者组在外显子组及2个过敏性疾病相关基因集范围内的功能缺失性变异和罕见非同义有害变异负荷均无显著差异。结论 过敏性疾病有明显遗传倾向，但全外显子测序结果显示未发现重复的变异基因，使得对于和过敏有关的基因需要进一步深入细致的研究。     

骨形态发生蛋白15基因单核苷酸多态性与卵巢早衰发病的相关性研究

目的探讨骨形态发生蛋白15(BMP15)基因编码区突变与中国汉族女性卵巢早衰(POF)发生的相关性。方法收集入院的103例中国汉族卵巢早衰患者作为疾病组,133例正常育龄女性为对照组,血样获取DNA后进行BMP15基因扩增,通过对PCR产物测序进行序列分析。结果发现编码区7处突变位点,其中4个为多态性位点,分别位于BMP15启动子区的rs3810683、第1外显子区的rs41308602、第2外显子区的rs79377927及rs17003221。与对照组相比,这4个SNP的基因型分布并未显示出统计学差异,仅有rs79377927的等位基因(TCT/-)分布在两组间差异有统计学意义(P0.05)。3个新的序列变异为第2外显子区的错义突变:381AG,617GA,661TC,均只出现在疾病组中。结论 BMP15基因编码区的rs79377927(788ins TCT)位点可能与POF的发病相关。     

通过外显子组测序对1例孤独症谱系障碍患者的致病基因分析

目的 应用外显子测序技术对1例孤独症谱系障碍的男童进行外显子组测序分析,寻找致病基因。方法 选择1例就读于自闭症特殊学校的5岁男童,收集其临床资料,提取外周静脉血DNA,应用Nimblegen外显子序列捕获芯片及高通量测序技术对外显子区域进行测序。结果 通过全外显子组捕获测序发现了非同义突变11 309个,移码突变365个,同义突变23 075个,其中发现有4个基因的突变已有文献报道可能与孤独症谱系障碍的发病有关,这4个基因包括PTEN、AFF2、LAMB1、NRCAM。结论 应用外显子组捕获测序对该例孤独症谱系障碍的男童进行测序分析显示,大量单核苷酸多态性可能与该病的发生有关,也进一步证实了PTEN、AFF2、LAMB1、NRCAM这4个基因可能与孤独症谱系障碍的发生有关,有待进一步大样本研究及实验室研究验证其在孤独症谱系障碍发病中的具体机制。     

肢带型肌营养不良2B型一例

肢带型肌营养不良是以骨盆带和肩胛带为主呈进行性肌肉改变的一组肌肉疾病,常在儿童期发病,具有明显的遗传异质性。报道1例因支气管肺炎就诊患儿,经全外显子组测序技术筛选相关基因变异位点,Sanger测序技术验证分析可疑变异位点。发现患儿DYSF基因（NM＿003494）存在外显子12位点c.2974T>C(p.W992R)和外显子28位点c. 1169A>G(p.D390G)的复合杂合变异,其中位点c.2974T>C(p.W992R)遗传自父亲,位点c.1169A>G(p.D390G)遗传自母亲。按照美国医学遗传学与基因组学学会指南二者均为截断变异（PVS1）且正常人群数据库未收录,均为罕见变异（PM2＿Supporting证据）,评估为可能致病性变异（likely pathogenic）。Sanger测序验证结果与全外显子组测序结果相一致,患儿最终诊断为肢带型肌营养不良2B型。全外显子组测序技术可为肢带型肌营养不良提供基因分析和产前诊断,在临床决策、遗传咨询及再次妊娠计划等方面具有关键性价值。     

新疆维吾尔族妇女子宫颈鳞癌组织C/EBPβ基因单核苷酸多态性分析

目的:探讨新疆维吾尔族妇女子宫颈鳞癌组织C/EBPβ基因启动子500 bp和外显子区序列的单核苷酸多态性位点。方法:C/EBPβ基因启动子500 bp和外显子区域设计6对引物,使用聚合酶链反应结合DNA测序方法分析15例维吾尔族妇女子宫颈鳞癌组织和2例子宫颈正常组织C/EBPβ基因序列。结果:C/EBPβ基因上检测出6个已知SNP位点和3个新发现的或低频的多态性位点,有1例标本检测发现在2091-2092处插入GGCGGCAGC 9个碱基,而在维吾尔族正常子宫颈组织未发现新多态性位点。结论:C/EBPβ基因上新的多态性位点可能与维吾尔族子宫颈鳞癌发生相关。     

DLX3基因罕见变异与发育性髋关节发育不良

目的:筛查DLX3基因(NM_005220)中发育性髋关节发育不良(DDH)相关的致病变异。方法:本研究对192例DDH患者和188例健康对照组的DLX3基因全部外显子区进行Sanger测序,排除已知高频单核苷酸多态性(SNP)位点(最小等位基因频率MAF≥1%)和对照组中存在的变异位点,结合功能性预测和保守性分析,最终筛选出DDH候选致病变异。结果:经过分析,最终在一个DDH患者中筛选出一个错义杂合变异DLX3c.G736C:p.D246H(rs3744539)可能为其致病突变,此变异在物种进化过程中高度保守且致病的可能性较高。结论:本研究首次对DLX3整个外显子区进行变异筛查,并发现新的DDH候选致病变异p.D246H。     

KCNQ2基因变异致不伴癫痫的全面性发育迟缓/智力障碍一例分析并文献复习

目的 总结KCNQ2基因变异相关不伴癫痫的全面性发育迟缓(GDD)/智力障碍(ID)患儿的临床特点及变异位点并进行文献复习，探讨KCNQ2基因变异与孤立性GDD/ID的相关性，明确患者病因。方法 收集2022年6月在丽水市妇幼保健院儿科就诊的1例不伴癫痫GDD/ID患儿及其家族成员的临床资料；提取患儿及其父母的外周血DNA,采用单核苷酸多态性微阵列分析及核心家系全外显子组测序进行遗传学分析。以“KCNQ2、intellectual disability/智力障碍、global developmental delay/全面性发育迟缓”为关键词，在HGMD、Pubmed、中国期刊全文数据库(CNKI)和万方医学文献数据库检索文献，检索时间为建库至2022年7月。收集文献已报道的KCNQ2基因变异相关不伴癫痫的GDD/ID病例，对所收集病例的临床资料及变异位点进行汇总分析。结果 先证者单核苷酸多态性微阵列分析未发现异常；全外显子组测序检测到与患儿表型相关的KCNQ2基因变异c.430C>T,为新发错义突变，根据ACMG标准评定为可能致病性变异。文献检索共收集到KCNQ2基因致病性变异相...     

ATRX新致病性变异致X连锁智力低下家系分析

目的：分析一个α地中海贫血X连锁智力障碍(ATR-X)综合征家系的致病基因突变。方法：对该ATR-X综合征家系先证者进行全外显子组测序,通过生物信息学分析筛选候选的致病基因突变位点,利用聚合酶链反应(PCR)和Sanger测序验证该家族成员的致病突变位点。结果：全外显子组测序发现先证者的X染色体ATRX基因存在半合子变异(c.161₁62del, p.Ser54Ter),家系成员Sanger测序结果表明该变异在家系中符合遗传共分离规律。结论：ATRX基因c.161₁62del变异为引起该家系ATR-X综合征的遗传学因素。     

遗传性男性不育的进展

遗传因素是男性不育的主要病因之一,并可通过辅助生殖技术垂直传递给男性子代。相当数量的临床非特发性重度少精子或无精子患者有AZF缺失。与精子发生有关的基因大量集中在Y染色体长臂的AZF区。在男性不育临床有必要开展使用外周血细胞DNA的AZF检查。     

CREM基因与特发性生精障碍关系的研究

目的探讨环磷酸腺苷反应元件调节物(CREM)基因与男性不育症中特发性生精障碍的关系。方法收集特发性无精子症和严重少精子症各20例患者的外周血,收集具有正常生育能力志愿者20例外周血作为对照。进行外周血提取DNA、聚合酶链反应(PCR)扩增、单链构象多态性(SSCP),检测特发性生精障碍患者外周血中CREM基因。结果在65%的无精子症和55%严重少精子症患者中检测出CREM基因的变异。结论在人类,CREM基因在精子的发生发育过程中起着至关重要的作用,CREM基因参与人类精子的发生。     

先天性双侧输精管缺如伴生精功能障碍一例

先天性双侧输精管缺如（congenital bilateral absence of vas deferens,CBAVD）是梗阻性无精子症的常见原因之一,睾丸生精功能一般正常,除了常见的囊性纤维化穿膜传导调节蛋白（cystic fibrosis transmembrane conductance regulator,CFTR）基因突变外,黏附G蛋白耦联受体G2（adhesion G protein-coupled receptor G2,ADGRG2）基因突变以及拷贝数变异也被认为是CBAVD的发病机制。本文报告1例CBAVD伴生精功能障碍的病例,睾丸组织病理学提示唯支持细胞综合征。全外显子组测序未发现该患者CFTR、ADGRG2以及无精子症相关基因存在致病变异,拷贝数变异分析也未发现有意义的拷贝数变异。该病例的确切遗传学病因尚未可知。CBAVD与生精功能障碍并存的临床现象,提示无精子症遗传病因的复杂性。     

CYP21A2基因复合杂合突变及多基因突变的男性无精症一例并文献复习

CYP21A2基因突变可引起21-羟化酶缺乏症,导致先天性肾上腺皮质增生症和性腺发育异常。根据CYP21A2基因突变位点不同,21-羟化酶缺乏症的临床表型存在异质性,成年患者常以生育障碍为首诊原因。CYP21A2基因突变同时合并多基因突变的复杂病例,国内外尚少见报道。报道1例CYP21A2基因c.518T>A/c.293-13A>G复合杂合突变的男性无精症病例,该患者合并DNAJB13/DNAI1/QRICH2J/FSIP2/HYDIN多基因突变,临床表型为男性不育症,经3个月糖皮质激素治疗后获得生精功能。该病例丰富了有关男性不育症的基因型,也为此类复合杂合基因突变疾病的诊治提供了临床经验。     

Analysis of the meiotic recombination gene REC8 for sequence variations in a population with severe male factor infertility

Proper regulation of meiosis is essential for normal spermatogenesis and abnormalities may be associated with infertility, as shown in both animal knockout studies and studies identifying anomalies in key proteins, such as SCP3 and MLH1. Disruptions of meiosis are associated with azoospermia or severe oligozoospermia, and may increase the incidence of sperm aneuploidy in some men. Based on its function and animal studies, REC8, a key component of the meiotic cohesion complex, has been identified as a candidate male infertility gene. In this study, we have evaluated sequence variation in the REC8 gene of severely infertile men of European descent with azoospermia or severe oligozoospermia compared to a fertile control population. The direct sequencing of these populations revealed nine polymorphic sites, four within intron/exon boarders, four within coding exons and one in the three prime untranslated region. These sites did not show significantly different allelic frequencies in the study populations compared to fertile controls. This indicates that polymorphisms of the Rec 8 gene are not a common cause of infertility in this population. Additional studies are warranted in patients with defined meiotic disruption.     

Genetic Risk Factors in Male Infertility

The etiopathogenesis of testicular failure remains unknown in about half of the cases and is referred to as “idiopathic infertility”. “Idiopathic” testicular failure is of probable genetic origin since the number of genes involved in human spermatogenesis is likely thousands and only a small proportion of them have been identified and screened in infertile men. In parallel with studies aimed to identify mutations with a clear cause-effect relationship in spermatogenesis candidate genes, there is an increasing interest towards genetic susceptibility factors to male infertility. Despite many efforts, only a few clinically relevant polymorphisms have been identified. This is mainly related to the multifactorial nature of male infertility and to the inappropriate study design of the majority of the studies. The most promising polymorphisms are in genes involved in the endocrine regulation of spermatogenesis and on the Y chromosome, the “gr/gr” deletions. Polymorphisms are generally considered as co-factors. Their final effect on testis function and fertility is probably modulated by the genetic background of each individual and/or by the presence of certain environmental factors. In this review, recent findings concerning some of the most widely studied polymorphisms and male infertility will be discussed.     

MOLECULAR BIOLOGY OF MALE INFERTILITY

About 15% of couples have reduced fertility and in approximately one-half of all cases the reason is male infertility, usually of genetic origin. Thus, in the context of research in genes involved in reproduction and sex determination, genetic anomalies in gametogenesis are being extensively studied. The most frequent pathogenic causes of male infertility are Y-chromosomal microdeletions (8-15%) in the long arm of the Y chromosome, which, by loss of specific DNA segments, leads to loss of vital genes for sperm production. Infertile men, who attend infertility clinics, rise to 15% among those with azoospermia or spermatogenesis problem. The new technique of intracytoplasmic sperm injection has allowed many infertile men to achieve their dreams of fatherhood. However, the spermatogenic defect is genetic anomalies, which might be a potential risk of transmitting this defect to future offspring. Therefore, genetic counseling of all couples with the diagnosis of male infertility is recommended before their enrolment in intrauterine insemination, in vitro fertilization, and intracytoplasmic sperm injection. The important role of genetic abnormalities in the causation of human male infertility is increasingly recognized. While much remains to be learned in this fast-moving field, considerable progress has been made in the clinical delineation of genetic forms of male infertility and in the characterization of the responsible genes and their mutations or deletions. This review should provide insight into the understanding of parthenogenesis of male infertility in the human.