Fraser Nicole S, Knauth Christine M, Schoeman Elizna M, Moussa Assia, Perkins Andrew C, Walsh Terry, Millard Glenda M, Dean Melinda M, Hyland Catherine A, Flower Robert L
Research and Development, Australian Red Cross Blood Service.
School of Biomedical Science, Faculty of Health, Queensland University of Technology, Brisbane, Australia.
Transfusion. 2018 Oct;58(10):2414-2420. doi: 10.1111/trf.14926. Epub 2018 Sep 17.
KLF1 is an essential transcriptional activator that drives erythropoiesis. KLF1 variants can result in the Inhibitor of Lutheran, or In(Lu), phenotype where red blood cells (RBCs) have reduced BCAM (LU) and CD44 (IN). Other RBC surface molecules also have changed expression; however, there is controversy in the literature regarding which are truly impacted. We aimed to investigate KLF1 variants in the Australian population.
In(Lu) samples were sourced through screening and through the RBC reference laboratory. Blood donor samples (8036) were screened to identify weakened/absent Lu antigen. Samples were genotyped by massively parallel sequencing, while surface carbohydrates and blood group molecules were assessed by flow cytometry. Hemoglobin (Hb) types were analyzed by high-performance liquid chromatography.
Four of 8036 donors were identified to be In(Lu), and two previously identified In(Lu) samples were provided from the RBC reference laboratory. Five different KLF1 variants were identified; two were novel: c.954G>C/p.Trp318Cys and c.421C>T/p.Arg141*. BCAM and CD44 were reduced in all samples, consistent with previous reports. As a group, In(Lu) RBCs had reduced CD35 (KN), ICAM4 (LW), and CD147 (OK), and demonstrated increased binding of lectins ECA and SNAI. One In(Lu) sample had elevated HbF and another elevated HbA2.
Different KLF1 variants may potentially produce variable phenotypes. A framework for investigating KLF1 variants and their phenotypic impact has been provided. In the future, given available international databases, further testing algorithms (as advocated here) will allow for correlation of phenotype with genotype and therefore accurately document this variability between KLF1 variants.
KLF1是驱动红细胞生成的一种重要转录激活因子。KLF1变体可导致路德抑制因子（In(Lu)）表型，即红细胞（RBC）的基底细胞黏附分子（BCAM，LU）和CD44（IN）减少。其他红细胞表面分子的表达也发生了变化；然而，关于哪些分子真正受到影响，文献中存在争议。我们旨在研究澳大利亚人群中的KLF1变体。
通过筛查和红细胞参考实验室获取In(Lu)样本。对8036份献血者样本进行筛查，以识别减弱/缺失的Lu抗原。通过大规模平行测序对样本进行基因分型，同时通过流式细胞术评估表面碳水化合物和血型分子。通过高效液相色谱分析血红蛋白（Hb）类型。
在8036名献血者中，有4人被鉴定为In(Lu)，红细胞参考实验室提供了另外2份先前鉴定的In(Lu)样本。鉴定出5种不同的KLF1变体；其中2种是新发现的：c.954G>C/p.Trp318Cys和c.421C>T/p.Arg141*。所有样本中的BCAM和CD44均减少，与先前报道一致。总体而言，In(Lu)红细胞的CD35（KN）、细胞间黏附分子4（ICAM4，LW）和CD147（OK）减少，并表现出凝集素ECA和SNAI的结合增加。1份In(Lu)样本的HbF升高，另1份的HbA2升高。
不同的KLF1变体可能产生不同的表型。本文提供了一个研究KLF1变体及其表型影响的框架。未来，鉴于现有的国际数据库，进一步的检测算法（如本文所倡导的）将使表型与基因型相关联，从而准确记录KLF1变体之间的这种变异性。
