Samaraweera Saumya E, Geukens Tatjana, Casolari Debora A, Nguyen Tran, Sun Caitlyn, Bailey Sheree, Moore Sarah, Feng Jinghua, Schreiber Andreas W, Parker Wendy T, Brown Anna L, Butcher Carolyn, Bardy Peter G, Osborn Michael, Scott Hamish S, Talaulikar Dipti, Grove Carolyn S, Hahn Christopher N, D'Andrea Richard J, Ross David M
Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, SA, Australia.
Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, SA, Australia; Department of Oncology, KU Leuven, Leuven, Belgium.
Pathology. 2023 Feb;55(1):77-85. doi: 10.1016/j.pathol.2022.05.015. Epub 2022 Aug 5.
The identification of a somatic mutation associated with myeloid malignancy is of diagnostic importance in myeloproliferative neoplasms (MPNs). Individuals with no mutation detected in common screening tests for variants in JAK2, CALR, and MPL are described as 'triple-negative' and pose a diagnostic challenge if there is no other evidence of a clonal disorder. To identify potential drivers that might explain the clinical phenotype, we used an extended sequencing panel to characterise a cohort of 44 previously diagnosed triple-negative MPN patients for canonical mutations in JAK2, MPL and CALR at low variant allele frequency (found in 4/44 patients), less common variants in the JAK-STAT signalling pathway (12 patients), or other variants in recurrently mutated genes from myeloid malignancies (18 patients), including hotspot variants of potential clinical relevance in eight patients. In one patient with thrombocytosis we identified biallelic germline MPL variants. Neither MPL variant was activating in cell proliferation assays, and one of the variants was not expressed on the cell surface, yet co-expression of both variants led to thrombopoietin hypersensitivity. Our results highlight the clinical value of extended sequencing including germline variant analysis and illustrate the need for detailed functional assays to determine whether rare variants in JAK2 or MPL are pathogenic.
在骨髓增殖性肿瘤（MPN）中，鉴定与髓系恶性肿瘤相关的体细胞突变具有诊断意义。在JAK2、CALR和MPL变异的常见筛查试验中未检测到突变的个体被描述为“三阴性”，如果没有其他克隆性疾病的证据，这会带来诊断挑战。为了确定可能解释临床表型的潜在驱动因素，我们使用了一个扩展测序面板，对44例先前诊断为三阴性MPN的患者队列进行分析，以检测JAK2、MPL和CALR中低变异等位基因频率的典型突变（在4/44例患者中发现）、JAK-STAT信号通路中较不常见的变异（12例患者）或髓系恶性肿瘤中反复突变基因的其他变异（18例患者），包括8例具有潜在临床相关性的热点变异。在1例血小板增多症患者中，我们鉴定出双等位基因种系MPL变异。在细胞增殖试验中，这两种MPL变异均未激活，其中一种变异在细胞表面未表达，但两种变异的共表达导致血小板生成素超敏反应。我们的结果突出了包括种系变异分析在内的扩展测序的临床价值，并说明了需要进行详细的功能试验来确定JAK2或MPL中的罕见变异是否具有致病性。
