Department of Hematogenetics, ICMR-National Institute of Immunohematology, King Edward Memorial Hospital Campus, Parel, Mumbai, 400012, India.
Department of Pediatrics, Kasturba Medical College Hospital, Manipal University, Mangalore, India.
Indian J Pediatr. 2019 Aug;86(8):692-699. doi: 10.1007/s12098-019-02928-1. Epub 2019 Apr 27.
Glucose-6-phosphate isomerase (GPI) deficiency is an autosomal recessive genetic disorder causing hereditary non-spherocytic hemolytic anemia (HNSHA) coupled with a neurological disorder. The aim of this study was to identify GPI genetic defects in a cohort of Indian patients with HNSHA coupled with neurological dysfunction.
Thirty-five patients were screened for GPI deficiency in the HNSHA patient group; some were having neurological dysfunction. Enzyme activity was measured by spectrophotometric method. The genetic study was done by single-stranded conformation polymorphism (SSCP) analysis, restriction fragment length polymorphism (RFLP) analysis by the restriction enzyme AciI for p.Arg347His (p.R347H) and confirmation by Sanger's sequencing.
Out of 35 patients, 15 showed 35% to 70% loss of GPI activity, leading to neurological problems with HNSHA. Genetic analysis of PCR products of exon 12 of the GPI gene showed altered mobility on SSCP gel. Sanger's sequencing revealed a homozygous c1040G > A mutation predicting a p.Arg347His replacement which abolishes AciI restriction site. The molecular modeling analysis suggests p.Arg347 is involved in dimerization of the enzyme. Also, this mutation generates a more labile enzyme which alters its three-dimensional structure and function.
This report describes the high prevalence of p.Arg347His pathogenic variant identified in Indian GPI deficient patients with hemolytic anemia and neuromuscular impairment. It suggests that neuromuscular impairment with hemolytic anemia cases could be investigated for p.Arg347His pathogenic variant causing GPI deficiency because of neuroleukin activity present in the GPI monomer which has neuroleukin action at the same active site and generates neuromuscular problems as well as hemolytic anemia.
葡萄糖-6-磷酸异构酶（GPI）缺乏症是一种常染色体隐性遗传疾病，可导致遗传性非球形红细胞溶血性贫血（HNSHA）合并神经功能障碍。本研究旨在鉴定伴有神经功能障碍的 HNSHA 印度患者群体中的 GPI 遗传缺陷。
对 35 例 HNSHA 患者进行 GPI 缺乏症筛查，其中部分患者存在神经功能障碍。通过分光光度法测量酶活性。通过单链构象多态性（SSCP）分析、限制酶 AciI 对 p.Arg347His（p.R347H）的限制片段长度多态性（RFLP）分析以及 Sanger 测序进行基因研究。
在 35 例患者中，有 15 例患者的 GPI 活性丧失了 35%至 70%，导致 HNSHA 伴有神经问题。GPI 基因第 12 外显子 PCR 产物的遗传分析显示 SSCP 凝胶上迁移率发生改变。Sanger 测序显示纯合 c1040G > A 突变预测 p.Arg347His 取代，从而破坏了 AciI 限制位点。分子建模分析表明 p.Arg347 参与了酶的二聚化。此外，该突变产生了更不稳定的酶，改变了其三维结构和功能。
本报告描述了在印度 GPI 缺乏伴溶血性贫血和神经肌肉损伤的患者中发现的高患病率 p.Arg347His 致病性变异。这表明，伴有神经肌肉损伤的溶血性贫血病例可以调查 p.Arg347His 致病性变异引起的 GPI 缺乏症，因为 GPI 单体中的神经白细胞素活性具有神经白细胞素作用，在同一活性部位产生神经肌肉问题以及溶血性贫血。
