Department of Pathology, University of Utah Health and ARUP Laboratories, Salt Lake City, Utah, USA.
ARUP Laboratories, Salt Lake City, Utah, USA.
Eur J Haematol. 2023 Jun;110(6):688-695. doi: 10.1111/ejh.13951. Epub 2023 Mar 8.
Hereditary hemolytic anemias (HHA) comprise a heterogeneous group of disorders resulting from defective red blood cell (RBC) cytoskeleton, RBC enzyme deficiencies, and hemoglobin (Hb) synthesis disorders such as thalassemia or sideroblastic anemia.
Our hemolytic anemia diagnostic next-generation sequencing (NGS) panel includes 28 genes encoding RBC cytoskeletal proteins, membrane transporter, RBC enzymes, and certain bilirubin metabolism genes. The panel covers the complete coding region of these genes, splice junctions, and, wherever appropriate, deep intronic or regulatory regions are also included. Four hundred fifty-six patients with unexplained hemolytic anemia were evaluated using our NGS panel between 2015 and 2019.
We identified pathogenic/likely pathogenic variants in 111/456 (24%) patients that were responsible for the disease phenotype (e.g., moderate to severe hemolytic anemia and hyperbilirubinemia). Approximately 40% of the mutations were novel. As expected, 45/456 (10%) patients were homozygous for the promoter polymorphism in the UGT1A1 gene, A(TA) TAA (UGT1A128). 8/45 homozygous UGT1A128 cases were associated with additional pathogenic mutations causing hemolytic anemia, likely exacerbating hyperbilirubinemia. The most common mutated genes were membrane cytoskeleton genes SPTA1, and SPTB, followed by PKLR. Complex interactions between SPTA1 low expression alleles, alpha-LELY and alpha-LEPRA alleles, and intragenic SPTA1 variants were associated with hereditary pyropoikilocytosis and autosomal recessive hereditary spherocytosis in 23/111 patients.
Our results demonstrate that hemolytic anemia is underscored by complex molecular interactions of previously known and novel mutations in RBC cytoskeleton/enzyme genes, and therefore, NGS should be considered in all patients with clinically unexplained hemolytic anemia and in neonates with hyperbilirubinemia. Moreover, low expression alleles alpha-LELY and alpha-LEPRA should be included in all targeted HHA panels.
遗传性溶血性贫血（HHA）是一组由红细胞（RBC）细胞骨架、RBC 酶缺陷以及血红蛋白（Hb）合成障碍（如地中海贫血或铁幼粒细胞性贫血）引起的遗传性疾病。
我们的溶血性贫血诊断下一代测序（NGS）面板包括 28 个编码 RBC 细胞骨架蛋白、膜转运蛋白、RBC 酶和某些胆红素代谢基因的基因。该面板涵盖了这些基因的完整编码区、剪接接头，并且在适当的情况下，还包括深内含子或调节区。2015 年至 2019 年期间，我们使用 NGS 面板评估了 456 名不明原因溶血性贫血患者。
我们在 111/456（24%）患者中发现了致病性/可能致病性变异，这些变异导致了疾病表型（例如，中度至重度溶血性贫血和高胆红素血症）。大约 40%的突变是新的。正如预期的那样，45/456（10%）患者为 UGT1A1 基因启动子多态性 A(TA)TAA（UGT1A128）的纯合子。8/45 例纯合 UGT1A128 病例与引起溶血性贫血的其他致病性突变相关，可能加重高胆红素血症。最常见的突变基因是膜细胞骨架基因 SPTA1 和 SPTB，其次是 PKLR。在 23/111 名患者中，SPTA1 低表达等位基因、alpha-LELY 和 alpha-LEPRA 等位基因以及内含子 SPTA1 变异之间的复杂相互作用与遗传性热不稳定血影蛋白溶血性贫血和常染色体隐性遗传性球形红细胞增多症相关。
我们的结果表明，溶血性贫血是由 RBC 细胞骨架/酶基因的先前已知和新突变的复杂分子相互作用引起的，因此，在所有具有临床不明原因溶血性贫血的患者和具有高胆红素血症的新生儿中都应考虑使用 NGS。此外，应在所有针对 HHA 的靶向面板中包含低表达等位基因 alpha-LELY 和 alpha-LEPRA。
