Telomere Diseases and Other Constitutional and Acquired Genetic Disorders of Hematopoiesis

在临床上，我们继续按照我们目前的低剂量达那唑方案招募患者，其中包括通过流式FISH进行端粒长度的辅助检测，以及延长的观察期和洗脱期（在大流行期间难以招募新患者）。在合作努力中，另一种雄激素deceturabolin decanoate成功地改善了血细胞计数和影响端粒延长，这使得免疫再生障碍性贫血与各种体质综合征（包括Fanconi贫血，端粒生物学障碍，RUNX 1缺乏症和Diamond-Blackfan贫血）的可靠区分成为可能。标准的血液学检查是足够的，但端粒长度是至关重要的预测准确性。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。我们正在与学术儿科中心联盟合作，扩展我们的机器学习方法，以改善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。 我们研究了端粒疾病和其他综合征患者中复发突变的骨髓恶性肿瘤基因的克隆性造血。除了一个例外，克隆造血的存在与临床表现、结果或存活率无关，这可能是由于克隆在体内扩增所需的时间。POT 1（与种系TINF 2突变相关）和TERT启动子区的第二个突变似乎挽救了端粒缺陷型。然而，在U2 AF 1，一个重要的剪接体基因突变的克隆，出现恶性肿瘤的驱动程序，并强烈与预后不良。 我们的诊所与NIAMS的同事协调，现在是VEXAS的主要转诊中心。除了详细的临床表征，我们现在正在积累的干预方案，在VEXAS造血干细胞移植;在最初的几个患者的植入已经没有问题，突变的克隆已被根除与我们的调理方案;并发症GVHD在这个老年人口已预期和管理。克隆性造血是VEXAS的特征，也是其他病理性炎症的特征。次级造血克隆在VEXAS患者中很常见，特别是涉及DNMT 3A，这是一种在不确定预后的克隆造血（CHIP）中也很常见的基因，以及涉及TET 2的较小克隆。同样模式的克隆性扩张在自身炎性疾病中也更常见，当调整年龄时，从年轻的川崎动脉炎患者到老年的血管炎综合征患者。我们已经使用单细胞DNA测序与错误校正，以证明可变的克隆结构在VEXAS的情况下：克隆通常来自潜在的UBA 1突变的干细胞，或在平行的分支模式。 单细胞RNA测序已成功应用于VEXAS骨髓样本。主要结果已经证明了早期髓系偏向，淋巴成熟不足，以及造血干细胞中最显著的炎症信号传导的广泛激活，涉及干扰素-γ和-α以及肿瘤坏死因子途径。令人惊讶的是发现了意想不到的T细胞克隆性，尽管患者中存在B细胞克隆表现如MGUS和多发性骨髓瘤，但在临床上并不明显，并且造血细胞中特异性错误折叠蛋白质降解途径上调。

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.