Telomere Diseases and Other Constitutional and Acquired Genetic Disorders of Hematopoiesis

在临床上，我们继续让患者接受我们目前的低剂量达那唑方案，其中包括通过Flow-FISH进行端粒长度的辅助测试，以及延长观察期和洗脱期(大流行期间很难招募新患者)。在合作的努力中，另一种雄激素--十氢呋喃十酸十酯在改善血细胞计数和影响端粒延长方面取得了成功，这使得免疫性再生障碍性贫血能够可靠地与各种体质综合征区分开来，包括Fanconi贫血、端粒生物学疾病、RUNX1缺乏症和Diamond-Blackfan贫血。标准的血液学检测已经足够，但端粒长度对预测准确性至关重要。我们的人工智能工具现在可以在NHLBI托管的网站上公开使用。我们正在与儿科学术中心联盟合作，扩展我们的机器学习方法，以提高对个体体质综合征的诊断，并在获得性再生障碍性贫血中区分低风险MDS和再生障碍性贫血，并预测再生障碍性贫血的克隆进化。我们在端粒病和其他综合征患者中检测了反复突变的髓系恶性肿瘤基因的克隆性造血作用。除了一个例外，克隆性造血的存在与临床表现、结果或存活率都没有相关性，可能是由于克隆在体内扩张所需的时间。第二，POT1(与生殖系TINF2突变相关)和TERT启动子区域的突变似乎挽救了端粒缺陷的表型。然而，重要的剪接体基因U2AF1突变的克隆似乎是恶性肿瘤的驱动因素，并与不良预后密切相关。 我们的诊所与NIAMS的同事合作，现在是VEXAS的主要转诊中心。除了详细的临床特征外，我们现在正在为VEXAS的造血干细胞移植制定介入方案；最初几个患者的植入没有问题，突变克隆已经通过我们的调节方案根除；GVHD在这一老年人群中的并发症如预期的那样可控。克隆性造血是VEXAS的一个特征，也是其他病理性炎症的一个特征。继发性造血克隆在VEXAS患者中很常见，尤其是涉及DNMT3A基因，该基因也经常出现在预后不确定的克隆性造血(CHIP)中，以及涉及TET2的较小克隆。当根据年龄进行调整后，在自体炎症性疾病中，从年轻的川崎动脉炎患者到患有脉管炎综合征的老年患者，相同模式的克隆性扩张通常也更常见。我们使用了带误差校正的单细胞DNA测序来展示VEXAS病例中不同的克隆结构：克隆通常来自潜在的UBA1突变的干细胞，或者平行地以分支模式出现。 单细胞RNA测序已成功地应用于VEXAS骨髓样本。主要结果已经证明，早期的髓系偏向，淋巴成熟不足，最显著的是造血干细胞中炎症信号的广泛激活，涉及干扰素-伽马和-α和肿瘤坏死因子途径。令人惊讶的是发现了意想不到的T细胞克隆性，尽管患者的B细胞克隆性表现如MGUS和多发性骨髓瘤，但临床上并不明显，而且造血细胞中特定的错误折叠蛋白降解途径上调。

In the clinic, we continue to accrue patients to our current protocol of low doses of danazol, which includes ancillary testing by flow-FISH for telomere length, and both extended observation and wash-out periods (new patients were difficult to recruit during the pandemic). In collaborative efforts, another androgen, decadurabolin decanoate, was successful in in improving blood counts and effecting telomere elongation, which allows reliable discrimination of immune aplastic anemia from a variety of constitutional syndromes including Fanconi anemia, telomere biology disorders, RUNX1 deficiency, and Diamond-Blackfan anemia. Standard hematologic tests are sufficient, but telomere length is crucial to predictive accuracy. Our artificial intelligence tool is now publicly available at an NHLBI-hosted website. We are extending our machine learning approaches in a collaboration with a consortium of academic pediatric centers to improve diagnosis of individual constitutional syndromes, and in acquired aplastic anemia to distinguish low risk MDS from aplastic anemia and to predict clonal evolution in aplastic anemia. We have examined clonal hematopoiesis in recurrently mutated myeloid malignancy genes in patients with telomere disease and other syndromes. With a single exception, the presence of clonal hematopoiesis does not correlate with either clinical manifestations, outcomes, or survival, perhaps due to the time required for clones to expand in vivo. Second mutations in POT1 (which associate with germline TINF2 mutations) and in the promoter region of TERT appear to rescue the telomere deficient phenotype. However, clones mutated in U2AF1, an important spliceasome gene, appear as drivers of malignancy and strongly associate with a poor prognosis. Our clinic, in coordination with colleagues in NIAMS, is now a major referral center for VEXAS. In addition to detailed clinical characterization, we are now accruing to an interventional protocol for hematopoietic stem cell transplantation in VEXAS; engraftment in the first few patients has been unproblematic and the mutated clones have been eradicated with our conditioning regimens; complications of GVHD in this older population have been as anticipated and manageable. Clonal hematopoiesis is a feature of VEXAS, and also of other sydromes of pathologic inflammation. Secondary hematopoietic clones are frequent in VEXAS patients, particularly involving DNMT3A, a gene also frequent in clonal hematopoiesis of indeterminate prognosis (CHIP), and smaller clones involving TET2. Clonal expansion of the same pattern is also more frequent in general in autoinflammatory diseases, when adjusted for age, in young patients with Kawasaki arteritis to older patients with vasculitic syndromes. We have used single cell DNA sequencing with error correction to demonstrate variable clonal architectures in VEXAS cases: clones usually arise from the underlying UBA1 mutated stem cell, or in a branched pattern in parallel. Single cell RNA sequencing has been successfully applied to VEXAS bone marrow samples. Major results have been evidence of early myeloid lineage bias, deficient lymphoid maturation, and most prominently broad activation of inflammatory signaling in hematopoietic stem cells, involving interferon-gamma and -alpha and tumor necrosis factor pathways. Surprising have been findings of unexpected T cell clonality, not evident clinically despite B cell clonal manifestations like MGUS and multiple myeloma in patients, and upregulation of specific misfolded protein degradation pathways in hematopoietic cells.