STUDY QUESTION Are ICSI outcomes impaired in cases of severe asthenozoospermia with multiple morphological abnormalities of the flagellum (MMAF phenotype)? SUMMARY ANSWER Despite occasional technical difficulties, ICSI outcomes for couples with MMAF do not differ from those of other couples requiring ICSI, irrespective of the genetic defect. WHAT IS KNOWN ALREADY Severe asthenozoospermia, especially when associated with the MMAF phenotype, results in male infertility. Recent findings have confirmed that a genetic aetiology is frequently responsible for this phenotype. In such situations, pregnancies can be achieved using ICSI. However, few studies to date have provided detailed analyses regarding the flagellar ultrastructural defects underlying this phenotype, its genetic aetiologies, and the results of ICSI in such cases of male infertility. STUDY DESIGN, SIZE, DURATION We performed a retrospective study of 25 infertile men exhibiting severe asthenozoospermia associated with the MMAF phenotype identified through standard semen analysis. They were recruited at an academic centre for assisted reproduction in Paris (France) between 2009 and 2017. Transmission electron microscopy (TEM) and whole exome sequencing (WES) were performed in order to determine the sperm ultrastructural phenotype and the causal mutations, respectively. Finally 20 couples with MMAF were treated by assisted reproductive technologies based on ICSI. PARTICIPANTS/MATERIALS, SETTING, METHODS Patients with MMAF were recruited based on reduced sperm progressive motility and increased frequencies of absent, short, coiled or irregular flagella compared with those in sperm from fertile control men. A quantitative analysis of the several ultrastructural defects was performed for the MMAF patients and for fertile men. The ICSI results obtained for 20 couples with MMAF were compared to those of 378 men with oligoasthenoteratozoospermia but no MMAF as an ICSI control group. MAIN RESULTS AND THE ROLE OF CHANCE TEM analysis and categorisation of the flagellar anomalies found in these patients provided important information regarding the structural defects underlying asthenozoospermia and sperm tail abnormalities. In particular, the absence of the central pair of axonemal microtubules was the predominant anomaly observed more frequently than in control sperm (P < 0.01). Exome sequencing, performed for 24 of the 25 patients, identified homozygous or compound heterozygous pathogenic mutations in CFAP43, CFAP44, CFAP69, DNAH1, DNAH8, AK7, TTC29 and MAATS1 in 13 patients (54.2%) (11 affecting MMAF genes and 2 affecting primary ciliary dyskinesia (PCD)-associated genes). A total of 40 ICSI cycles were undertaken for 20 MMAF couples, including 13 cycles (for 5 couples) where a hypo-osmotic swelling (HOS) test was required due to absolute asthenozoospermia. The fertilisation rate was not statistically different between the MMAF (65.7%) and the non-MMAF (66.0%) couples and it did not differ according to the genotype or the flagellar phenotype of the subjects or use of the HOS test. The clinical pregnancy rate per embryo transfer did not differ significantly between the MMAF (23.3%) and the non-MMAF (37.1%) groups. To date, 7 of the 20 MMAF couples have achieved a live birth from the ICSI attempts, with 11 babies born without any birth defects. LIMITATIONS, REASONS FOR CAUTION The ICSI procedure outcomes were assessed retrospectively on a small number of affected subjects and should be confirmed on a larger cohort. Moreover, TEM analysis could not be performed for all patients due to low sperm concentrations, and WES results are not yet available for all of the included men. WIDER IMPLICATIONS OF THE FINDINGS An early and extensive phenotypic and genetic investigation should be considered for all men requiring ICSI for severe asthenozoospermia. Although our study did not reveal any adverse ICSI outcomes associated with MMAF, we cannot rule out that some rare genetic causes could result in low fertilisation or pregnancy rates. STUDY FUNDING/COMPETING INTEREST(S) No external funding was used for this study and there are no competing interests. TRIAL REGISTRATION NUMBER N/A.

中文翻译：

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重度弱精子症伴多种鞭毛形态异常的基因诊断、精子表型和ICSI结果

研究问题 在伴有多种鞭毛形态异常（MMAF 表型）的严重弱精子症病例中，ICSI 结果是否受损？总结答案 尽管偶尔会遇到技术困难，但无论遗传缺陷如何，MMAF 夫妇的 ICSI 结果与其他需要 ICSI 的夫妇没有区别。已知情况 严重的弱精子症，尤其是与 MMAF 表型相关时，会导致男性不育。最近的研究结果证实，遗传病因通常是造成这种表型的原因。在这种情况下，可以使用 ICSI 实现怀孕。然而，迄今为止，很少有研究提供有关这种表型背后的鞭毛超微结构缺陷、其遗传病因以及 ICSI 在此类男性不育病例中的结果的详细分析。研究设计、规模、持续时间 我们对 25 名不育男性进行了一项回顾性研究，这些男性表现出与通过标准精液分析确定的 MMAF 表型相关的严重弱精子症。他们于 2009 年至 2017 年在巴黎（法国）的辅助生殖学术中心被招募。进行透射电子显微镜 (TEM) 和全外显子组测序 (WES) 以分别确定精子超微结构表型和因果突变。最终对20对MMAF夫妇进行了基于ICSI的辅助生殖技术治疗。参与者/材料、设置、方法 MMAF 患者的招募是基于与可生育对照男性的精子相比，精子进行性运动减少以及缺少、短、卷曲或不规则鞭毛的频率增加。对 MMAF 患者和有生育能力的男性进行了几种超微结构缺陷的定量分析。将 20 对患有 MMAF 的夫妇的 ICSI 结果与作为 ICSI 对照组的 378 名患有少弱畸形精子症但没有 MMAF 的男性进行比较。主要结果和 CHANCE 的作用 TEM 分析和在这些患者中发现的鞭毛异常分类提供了有关弱精子症和精子尾部异常的结构缺陷的重要信息。特别是，中心轴丝微管对的缺失是比对照精子更频繁观察到的主要异常（P < 0.01）。对 25 名患者中的 24 名进行外显子组测序，鉴定出 CFAP43、CFAP44、CFAP69、DNAH1、DNAH8、AK7、13 名患者 (54.2%) 中的 TTC29 和 MAATS1（11 名影响 MMAF 基因，2 名影响原发性纤毛运动障碍 (PCD) 相关基因）。总共为 20 对 MMAF 夫妇进行了 40 个 ICSI 周期，其中 13 个周期（5 对夫妇）由于绝对弱精子症而需要进行低渗透肿胀 (HOS) 测试。受精率在 MMAF (65.7%) 和非 MMAF (66.0%) 夫妇之间没有统计学差异，并且根据受试者的基因型或鞭毛表型或 HOS 测试的使用没有差异。每次胚胎移植的临床妊娠率在 MMAF（23.3%）和非 MMAF（37.1%）组之间没有显着差异。迄今为止，20 对 MMAF 夫妇中有 7 对通过 ICSI 尝试实现了活产，其中 11 名婴儿出生时没有任何出生缺陷。限制，谨慎的原因 ICSI 程序结果在少数受影响的受试者中进行了回顾性评估，并应在更大的队列中得到确认。此外，由于精子浓度低，无法对所有患者进行 TEM 分析，并且尚未获得所有纳入男性的 WES 结果。研究结果的更广泛意义 应考虑对所有因严重弱精子症需要 ICSI 的男性进行早期和广泛的表型和遗传学调查。尽管我们的研究没有发现任何与 MMAF 相关的不良 ICSI 结果，但我们不能排除一些罕见的遗传原因可能导致低受精率或妊娠率。研究资金/竞争利益 本研究没有使用外部资金，也没有竞争利益。试用注册号 不适用。