Klinefelter syndrome (KS), also known as 47, XXY, is characterized by a distinct set of physiological abnormalities, commonly including infertility. The molecular basis for Klinefelter-related infertility is still unclear, largely because of the cellular complexity of the testis and the intricate endocrine and paracrine signaling that regulates spermatogenesis. Here, we demonstrate an analysis framework for dissecting human testis pathology that uses comparative analysis of single-cell RNA-sequencing data from the biopsies of 12 human donors. By comparing donors from a range of ages and forms of infertility, we generate gene expression signatures that characterize normal testicular function and distinguish clinically distinct forms of male infertility. Unexpectedly, we identified a subpopulation of Sertoli cells within multiple individuals with KS that lack transcription from the XIST locus, and the consequence of this is increased X-linked gene expression compared to all other KS cell populations. By systematic assessment of known cell signaling pathways, we identify 72 pathways potentially active in testis, dozens of which appear upregulated in KS. Altogether our data support a model of pathogenic changes in interstitial cells cascading from loss of X inactivation in pubertal Sertoli cells and nominate dosage-sensitive factors secreted by Sertoli cells that may contribute to the process. Our findings demonstrate the value of comparative patient analysis in mapping genetic mechanisms of disease and identify an epigenetic phenomenon in KS Sertoli cells that may prove important for understanding causes of infertility and sex chromosome evolution.

Klinefelter 综合征 (KS)，也称为 47，XXY，其特征是一组明显的生理异常，通常包括不孕症。Klinefelter 相关不孕症的分子基础仍不清楚，主要是因为睾丸的细胞复杂性以及调节精子发生的复杂内分泌和旁分泌信号。在这里，我们展示了一个用于解剖人类睾丸病理的分析框架，该框架使用来自 12 名人类供体活检的单细胞 RNA 测序数据的比较分析。通过比较来自不同年龄和不育形式的捐赠者，我们生成了表征正常睾丸功能的基因表达特征，并区分临床上不同形式的男性不育症。不料，XIST基因座，其结果是与所有其他 KS 细胞群相比 X 连锁基因表达增加。通过对已知细胞信号通路的系统评估，我们确定了 72 条可能在睾丸中活跃的通路，其中几十条在 KS 中出现上调。总而言之，我们的数据支持间质细胞的致病变化模型，该模型因青春期支持细胞中 X 失活的丧失而发生级联，并指定了支持细胞分泌的可能有助于该过程的剂量敏感因子。我们的研究结果证明了比较患者分析在绘制疾病遗传机制和确定 KS 支持细胞中的表观遗传现象方面的价值，这可能对理解不孕症和性染色体进化的原因很重要。