伴SLC4A1罕见突变遗传性球形红细胞增多症1例的临床分析并文献复习

Clinical analysis of a case of hereditary spherocytosis with a rare SLC4A1 mutation and literature review

目的探讨遗传性球形红细胞增多症(HS)患者的临床特点、基因突变检查结果及诊疗方法,并且进行相关文献复习。方法选择2021年10月24日重庆医科大学附属儿童医院血液肿瘤科收治的1例8岁3个月男性HS合并室间隔缺损患儿为研究对象。采用回顾性分析方法,收集患儿病史、家族史资料,以及实验室及影像学检查结果,对患儿的临床表现、基因突变与诊疗过程进行分析。对患儿的随访截至2022年4月30日。进一步采集患儿及其父母外周血样进行基因测序,对检出的SLC4A1突变采用SIFT、PolyPhen-2、REVEL等遗传变异有害性预测工具评估蛋白结构功能的保守性。利用Swiss Model在线工具分析预测突变对于蛋白质结构的影响。以"遗传性球形红细胞增多症""SLC4A1基因""hereditary spherocytosis""SLC4A1"为中、英文关键词,在中国知网数据库、万方数据知识服务平台及PubMed数据库中检索HS相关文献,并对文献报道的HS患者进行分析和总结。文献检索时间设定为2019年1月1日至2022年4月29日。本研究获得重庆医科大学附属儿童医院伦理委员会审批(批准文号:2021.457),并与患儿家属签署临床研究知情同意书。结果①本例患儿因"面色苍黄加重2个月+"就诊。患儿面色苍黄,病程中间断出现茶色尿,中度贫血,肝、脾大合并先天性室间隔缺损(膜周融合型)。血常规检查结果示,白细胞计数为7.06×10^(9)/L,红细胞计数为2.41×10^(12)/L,血红蛋白(Hb)值为64 g/L,平均红细胞体积(MCV)为94.6 fL,平均血红蛋白浓度(MCHC)值为281 g/L,网织红细胞百分比为11.47%。外周血涂片检查结果示,患儿外周血球形红细胞比例为18.3%。生化全项检查结果示,总胆红素水平为53.1μmol/L,直接胆红素水平为15.7μmol/L,间接胆红素水平为37.4μmol/L,乳酸脱氢酶水平为439 U/L。红细胞渗透脆性增加。基因测序结果示,患儿携带SLC4A1基因12号外显子c.1387G>A(p.Gly463Ser)罕见杂合错义突变,该突变来源于其父,预测为有害致病基因突变。患儿父亲未表现出贫血、溶血相关症状,仅外周血涂片可见少量球形红细胞。Swiss Model在线工具分析预测结果示,突变型SLC4A1蛋白的三级结构未因氨基酸替换受到影响。②根据患儿临床表现及基因检查结果,本例患儿被诊断为HS。患儿接受红细胞成分血输注及脾切除术,治疗后患儿临床症状基本消失,处于部分缓解状态。截至随访结束,患儿一般情况良好,拟择期行后续心室间隔缺损手术。③根据本研究设定的文献检索策略,共检索出5篇HS文献,报道6例HS患者,加上本研究1例,共纳入7例HS患者。其中,1例患者临床表现为皮肤黄染并远端肾小管酸中毒(dRTA),无HS家族史,SLC4A1错义突变致病。1例患者伴反复低血钾,外周血细胞形态学检查结果可见大量球形红细胞,有HS家族史,SLC4A1错义突变致病。1例患者伴反复不明原因贫血,有HS家族史,SLC4A1缺失突变致病。2例患者面色苍白、黄疸,SLC4A1新发错义突变致病。1例伴黄疸、胆石症,有HS家族史,SLC4A1错义突变致病。本例患儿面色苍黄,有HS家族史,SLC4A1错义突变致病。结论本例HS患儿家系为SLC4A1基因12号外显子c.1387G>A(p.Gly463Ser)罕见杂合错义突变致病。基因突变检查有助于HS的确诊。

Objective To investigate clinical characteristics,gene sequencing results and treatment of patients with hereditary spherocytosis(HS),and review the relevant literature.Methods On October 24,2021,a case of 8 years and 3 months old male child with HS combined by ventricular septal defect admitted to Department of Hematology and Oncology,Children′s Hospital of Chongqing Medical University,was enrolled as subject.Using a retrospective analysis method,the child′s medical history,family history,laboratory and imaging examination results were collected,and clinical manifestations,gene mutations,diagnosis and treatment process of the child were analyzed.Follow-up of the child was conducted until April 30,2022.Furthermore,peripheral blood samples were collected from the child and his parents for gene sequencing.Harmfulness of the detected SLC4A1 mutations was evaluated by genetic variation prediction tools such as SIFT,PolyPhen-2,and REVEL to assess the conservation of protein structure and function.Impact of predicted mutations on protein structure was analyzed using the Swiss Model online tool.Key words"hereditary spherocytosis","SLC4A1 gene","SLC4A1"in Chinese and English were used to search the literature related to HS in China Knowledge Network database,Wanfang Data Knowledge Service Platform and PubMed database,and to analyze and summarize the HS patients reported in literature.Time for literature retrieval was set from January 1,2019 to April 29,2022.The study was approved by the Ethics Committee of the Children′s Hospital of Chongqing Medical University(Approval No.2021.457),and the informed consent for the clinical study was signed with the families of the child.Results①The child was admitted due to"pallor aggravated for more than 2 months".He presented with pale yellow face,intermittent tea-colored urine,moderate anemia,hepatomegaly and splenomegaly combined with congenital ventricular septal defect(perimembranous fusion type).Routine blood test result showed that white blood cell count was 7.06×10^(9)/L,red blood cell count was 2.41×10^(12)/L,hemoglobin(Hb)value was 64 g/L,mean corpuscular volume(MCV)was 94.6 fL,mean corpuscular Hb concentration(MCHC)was 281 g/L,and reticulocyte was 11.47%.Peripheral blood smear result showed that the percentage of spherical red blood cells was 18.3%.Result of the biochemical examination showed total bilirubin was 53.1μmol/L,direct bilirubin was 15.7μmol/L,indirect bilirubin was 37.4μmol/L,and lactate dehydrogenase was 439 U/L.Erythrocyte osmotic fragility was increased.Gene sequencing results suggested that the child carried a rare heterozygous missense mutation in exon 12 of the SLC4A1 gene,c.1387G>A(p.Gly463Ser),which was paternally derived and predicted to be a deleterious pathogenic mutation.The father of the child did not show symptoms related to anemia or hemolysis,and only a few spherical red blood cells were seen on peripheral blood smear.Result of Swiss Model online tool showed that the tertiary structure of the mutant SLC4A1 protein was not affected by the amino acid substitution.②Based on the child′s clinical presentation and genetic findings,the diagnosis of HS was clear in this case.The child received red blood cell component blood transfusion and splenectomy.And after treatment,the child′s clinical symptoms basically disappeared and was in partial remission.As of the end of follow-up,the general condition was good,and follow-up surgery for ventricular septal defect was proposed at an optional date.③According to the literature search strategy set in this study,five HS articles were retrieved,reporting 6 cases of HS patients.And together with 1 case in this study,a total of 7 HS patients were included.One case of patient presented clinically with yellow skin staining and distal renal tubular acidosis(dRTA),with no HS family history and SLC4A1 missense mutation causing the disease.A case of patient with recurrent hypokalemia and a large number of spherical erythrocytes on peripheral blood morphology had a HS family history and SLC4A1 missense mutation causing the disease.A case of patient with recurrent complaints of unexplained anemia had a HS family history and SLC4A1 deletion mutation causing the disease.Two case of patients with pallor and jaundice had de novo SLC4A1 missense mutation.A case of patient with jaundice and cholelithiasis,had a HS family history and SLC4A1 missense mutation causing the disease.This case of child is pale and yellow,had a HS family history and SLC4A1 missense mutation causing the disease.Conclusions Rare heterozygous missense mutation in exon 12 c.1387G>A(p.Gly463Ser)of SLC4A1 was the genetic cause of the disease in this family.Genetic testing for mutations helped to confirm diagnosis of HS.