Medical Centre for Molecular Biology, Faculty of Medicine, Institute of Biochemistry and Molecular Genetics, University of Ljubljana, Ljubljana, Slovenia.
Centre for Functional Genomics and Bio-Chips, Faculty of Medicine, Institute of Biochemistry and Molecular Genetics, University of Ljubljana, Ljubljana, Slovenia.
J Clin Lab Anal. 2021 Apr;35(4):e23715. doi: 10.1002/jcla.23715. Epub 2021 Feb 3.
Erythrocytosis is a condition with an excessive number of erythrocytes, accompanied by an elevated haemoglobin and/or haematocrit value. Congenital erythrocytosis has a diverse genetic background with several genes involved in erythropoiesis. In clinical practice, nine genes are usually examined, but in approximately 70% of patients, no causative mutation can be identified. In this study, we screened 39 genes, aiming to identify potential disease-driving variants in the family with erythrocytosis of unknown cause.
Two affected family members with elevated haemoglobin and/or haematocrit and negative for acquired causes and one healthy relative from the same family were selected for molecular-genetic analysis of 24 erythrocytosis and 15 hereditary haemochromatosis-associated genes with targeted NGS. The identified variants were further analysed for pathogenicity using various bioinformatic tools and review of the literature.
Of the 12 identified variants, two heterozygous variants, the missense variant c.471G>C (NM_022051.2) (p.(Gln157His)) in the EGLN1 gene and the intron variant c.2572-13A>G (NM_004972.3) in the JAK2 gene, were classified as low-frequency variants in European population. None of the two variants were present in a healthy family member. Variant c.2572-13A>G has potential impact on splicing by one prediction tool.
For the first time, we included 39 genes in the erythrocytosis clinical panel and identified two potential disease-driving variants in the Slovene family studied. Based on the reported functional in vitro studies combined with our bioinformatics analysis, we suggest further functional analysis of variant in the JAK2 gene and evaluation of a cumulative effect of both variants.
红细胞增多症是一种红细胞数量过多的病症，伴随着血红蛋白和/或血细胞比容值升高。先天性红细胞增多症具有多种遗传背景，涉及多个参与红细胞生成的基因。在临床实践中，通常检查九个基因，但约 70%的患者无法确定致病突变。在这项研究中，我们筛选了 39 个基因，旨在鉴定原因不明的红细胞增多症家族中潜在的疾病驱动变异。
选择两名血红蛋白和/或血细胞比容升高且无获得性原因的受影响家族成员，以及同一家族的一名健康亲属，进行 24 个红细胞增多症和 15 个遗传性血色素沉着症相关基因的靶向 NGS 分子遗传学分析。使用各种生物信息学工具和文献回顾对鉴定出的变异进行致病性分析。
在 12 个鉴定出的变异中，两个杂合变异，即 EGLN1 基因中的错义变异 c.471G>C（NM_022051.2）（p.（Gln157His））和 JAK2 基因中的内含子变异 c.2572-13A>G（NM_004972.3），被归类为欧洲人群中的低频变异。这两个变异均不存在于健康的家族成员中。预测工具提示变异 c.2572-13A>G 可能对剪接有影响。
这是我们首次在红细胞增多症临床panel 中纳入 39 个基因，并在斯洛文尼亚研究的家族中鉴定出两个潜在的疾病驱动变异。基于报道的体外功能研究并结合我们的生物信息学分析，我们建议对 JAK2 基因中的变异进行进一步的功能分析，并评估两个变异的累积效应。
