LZTR1基因Arg284His变异致Noonan综合征10型病例报道和遗传学分析

doi:10.3969/j.issn.1673-8640.2024.02.004

摘要/Abstract

摘要：

目的对1例Noonan综合征10型(NS10)患儿进行临床特征和遗传学分析。方法对患儿及其父母进行家系全外显子组(trio-WES)检测，采用生物信息学方法对基因变异进行危害性分析，预测变异蛋白结构功能，采用免疫印迹法检测变异蛋白的表达量。结果患儿年龄为8岁9个月，临床表现为生长发育迟缓、先天性心脏病和特殊面容等。基因检测结果提示患儿亮氨酸拉链样转录调控因子1(LZTR1)基因发生杂合变异c.851G>A(p.Arg284His)(NM_6767.4)，其父亲携带该变异，母亲为野生型。Pubmed数据库和HGMD数据库未检索到相应变异的报道，属LZTR1基因新变异。SIFT、Polyphen-2和MutationTaster在线软件分析结果显示到LZTR1 c.851G>A(p.Arg 284His)变异存在生物危害性。蛋白结构模型分析结果显示，LZTR1 c.851G>A(p.Arg 284His)变异可导致LZTR1蛋白局部结构改变。免疫印迹法结果显示，与野生型LZTR1蛋白比较，变异型LZTR1蛋白的表达量降低了81.20 %。结论 LZTR1基因c.851G>A(p.Arg 284His)变异可能是NS10的致病原因。

关键词: 亮氨酸拉链样转录调控因子1, Noonan综合征, 基因检测, 家系全外显子组, 蛋白免疫印迹

Abstract:

Objective To investigate the clinical characteristics and perform the genetic analysis of a child of Noonan syndrome type 10(NS10). Methods The child and parents underwent trio-whole exome sequencing，and the variant was analyzed for harmfulness through bioinformatics. The protein structure function of variant was predicted，and western blot was conducted to analyze the expression level of variant protein. Results The patient was an 8-year-9-month-old boy with clinical manifestations including growth retardation，congenital heart disease，special face and so on. Genetic testing revealed a variant in leucine zipper like transcription regulator 1(LZTR1)gene，c.851G>A(p.Arg284His)(NM_6767.4)，which was inherited from his father，while his mother had the wild-type allele. This variant was new in LZTR1 gene，and there was no found in databases such as Pubmed and HGMD. SIFT，Polyphen-2 and MutationTaster online software analysis showed that LZTR1 c.851G>A(p.Arg 284His) was biohazardous. The results of protein structure model analysis showed that LZTR1 c.851G>A(p.Arg 284His) could lead to local structural changes of LZTR1 protein. Western blot results showed that the expression of variant-type LZTR1 protein was reduced by 81.20% compared with wild-type LZTR1 protein. Conclusions LZTR1 c.851G>A(p.Arg 284His) may be a pathogenic factor for NS10.

Key words: Leucine zipper like transcription regulator 1, Noonan syndrome, Genetic testing, Trio-whole exome sequencing, Western blot

中图分类号:

R446.7

诸宏伟, 张雪灵, 王美娣, 郑迎娟. LZTR1基因Arg284His变异致Noonan综合征10型病例报道和遗传学分析[J]. 检验医学, 2024, 39(2): 120-125.

ZHU Hongwei, ZHANG Xueling, WANG Meidi, ZHENG Yingjuan. Case report and genetic analysis of Noonan syndrome type 10 caused by Arg284His variant of LZTR1 gene[J]. Laboratory Medicine, 2024, 39(2): 120-125.

图/表 4

表1 本例患儿rhGH治疗和随访数据

治疗次数	年龄	身高/cm	体重/kg	IGF-1/(ng·mL^-1)	IGFBP-3/(ng·mL^-1)	FT₄^①/(ng·mL^-1)	TSH^②/(μIU·mL^-1)	INS^③/ (mIU·mL^-1)	HbA_1c^④/ %
1	9岁	123.5	21	57.1	2.98	0.92	3.08	4.90	5.00
2	9岁3个月	126.5	21	139	3.36	0.97	1.99	6.83	5.10
3	9岁6个月	129.2	22	196	3.86	0.99	2.64	5.98	5.20
4	9岁10个月	132.3	22	268	3.99	1.26	2.68	5.22	5.10

图1 本例患儿Sanger测序图注：患儿LZTR1基因发生变异c.851G>A(p.Arg284His)，其父亲携带该变异，母亲为野生型，Sanger测序证实存在该变异(红色箭头)。

图2 LZTR1蛋白Arg284变异保守性和结构预测分析注：(a)LZTR1蛋白Arg284在多物种间具有高度保守性(红色箭头)；(b)蛋白结构预测；Arg284His变异可导致与Gln282间氢键断裂。

图3 变异蛋白的功能分析注：(a)Sanger测序证实重组质粒转染至293T细胞；(b)免疫印迹图；(c)转染不同质粒的293T细胞LZTR1蛋白表达量比较。

参考文献 21

[1]	STEKLOV M, PANDOLFI S, BAIETTI M F, et al. Mutations in LZTR1 drive human disease by dysregulating RAS ubiquitination[J]. Science, 2018, 362(6419):1177-1182. DOI URL
[2]	CHEN R H. Cullin 3 and its role in tumorigenesis[J]. Adv Exp Med Biol, 2020, 1217:187-210.
[3]	ROBERTS A E, ALLANSON J E, TARTAGLIA M, et al. Noonan syndrome[J]. Lancet, 2013, 381(9863):333-342. DOI PMID
[4]	AOKI Y, NIIHORI T, INOUE S, et al. Recent advances in RASopathies[J]. J Hum Genet, 2016, 61(1):33-39. DOI PMID
[5]	UMEKI I, NIIHORI T, ABE T, et al. Delineation of LZTR1 mutation-positive patients with Noonan syndrome and identification of LZTR1 binding to RAF1-PPP1CB complexes[J]. Hum Genet, 2019, 138(1):21-35. DOI PMID
[6]	LI X, YAO R, TAN X, et al. Molecular and phenotypic spectrum of Noonan syndrome in Chinese patients[J]. Clin Genet, 2019, 96(4):290-299. DOI PMID
[7]	ZHAO X, LI Z, WANG L, et al. A Chinese family with Noonan syndrome caused by a heterozygous variant in LZTR1:a case report and literature review[J]. BMC Endocr Disord, 2021, 21(1):2. DOI
[8]	RICHARDS S, AZIZ N, BALE S, et al. Standards and guidelines for the interpretation of sequence variants:a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology[J]. Genet Med, 2015, 17(5):405-424.
[9]	YAMAMOTO G L, AGUENA M, GOS M, et al. Rare variants in SOS2 and LZTR1 are associated with Noonan syndrome[J]. J Med Genet, 2015, 52(6):413-421. DOI PMID
[10]	MOTTA M, FIDAN M, BELLACCHIO E, et al. Dominant Noonan syndrome-causing LZTR1 mutations specifically affect the Kelch domain substrate-recognition surface and enhance RAS-MAPK signaling[J]. Hum Mol Genet, 2019, 28(6):1007-1022. DOI PMID
[11]	中华医学会医学遗传学分会遗传病临床实践指南撰写组. Noonan综合征的临床实践指南[J]. 中华医学遗传学杂志, 2020, 37(3):324-328.
[12]	ZENKER M, EDOUARD T, BLAIR J C, et al. Noonan syndrome:improving recognition and diagnosis[J]. Arch Dis Child, 2022, 107(12):1073-1078. DOI URL
[13]	JOHNSTON J J, VAN DER SMAGT J J, ROSENFELD J A, et al. Autosomal recessive Noonan syndrome associated with biallelic LZTR1 variants[J]. Genet Med, 2018, 20(10):1175-1185. DOI URL
[14]	CHEN P C, YIN J, YU H W, et al. Next-generation sequencing identifies rare variants associated with Noonan syndrome[J]. Proc Natl Acad Sci U S A, 2014, 111(31):11473-11478. DOI URL
[15]	PAGNAMENTA A T, KAISAKI P J, BENNETT F, et al. Delineation of dominant and recessive forms of LZTR1-associated Noonan syndrome[J]. Clin Genet, 2019, 95(6):693-703. DOI PMID
[16]	HEBRON K E, HERNANDEZ E R, YOHE M E. The RASopathies:from pathogenetics to therapeutics[J]. Dis Model Mech, 2022, 15(2):dmm049107. DOI URL
[17]	NYSTRÖM A M, EKVALL S, BERGLUND E, et al. Noonan and cardio-facio-cutaneous syndromes:two clinically and genetically overlapping disorders[J]. J Med Genet, 2008, 45(8):500-506. DOI URL
[18]	KERR B, DELRUE M A, SIGAUDY S, et al. Genotype-phenotype correlation in Costello syndrome:HRAS mutation analysis in 43 cases[J]. J Med Genet, 2006, 43(5):401-405. DOI URL
[19]	ROHRER T R, ABUZZAHAB J, BACKELJAUW P, et al. Long-term effectiveness and safety of childhood growth hormone treatment in Noonan syndrome[J]. Horm Res Paediatr, 2020, 93(6):380-395. DOI URL
[20]	HORIKAWA R, OGATA T, MATSUBARA Y, et al. Long-term efficacy and safety of two doses of Norditropin^®(somatropin)in Noonan syndrome:a 4-year randomized,double-blind,multicenter trial in Japanese patients[J]. Endocr J, 2020, 67(8):803-818. DOI URL
[21]	DAHLGREN J, NOORDAM C. Growth,endocrine features,and growth hormone treatment in Noonan syndrome[J]. J Clin Med, 2022, 11(7):2034. DOI URL