先天性甲状腺功能减低患者TG基因突变筛查与研究

发布时间：2018-03-30 17:07

本文选题：先天性甲状腺功能减低症　切入点：甲状腺球蛋白基因　出处：《西北大学》2017年硕士论文

【摘要】：先天性甲状腺功能减低症(Congenital hypothyroidism,CH)是一种常见的婴幼儿内分泌疾病,可能导致儿童生长缓慢及智力发育迟缓。以前的研究发现许多与甲状腺素合成相关的基因的突变与CH的发生相关。甲状腺球蛋白基因(TG)是甲状腺激素合成的基质,在前人研究中TG突变使得甲状腺素合成和分泌过程受到影响,是导致CH的重要原因之一。本研究以来自西安地区的130例CH患者为和100例健康个体为研究对象,采用高通量测序的方法对CH患者的TG基因的外显子进行检测。筛查突变位点,研究西北地区人群TG的突变谱,分析TG基因突变在CH发病过程中的分子机制。在130例CH患者中,共发现24个可能导致CH发病的TG突变,4为个无义突变,3个为剪接突变和17个为错义突变。新发现的突变有8个,包括c.4641_4641delG,c.2060_2060delG,c.2864_2864delA,c.6840_6843delTTGT,c.3139+2TC,c.3634-ldelG,c.1514GA,c.7182CG,它们在健康对照组中的频率均小于1%。计算生物学预测结果表明12种突变为有害突变,12种为良性突变。将人的与牛,猪,猩猩,小鼠和大鼠的TG蛋白进行同源性比较,发现突变p.Arg1202Cys,p.Pro2236Leu,p.Ile2394Met,p.Arg2585Trp 处于 TG 的保守区。而 2236,2394,2585位氨基酸处于TG蛋白的功能域中。利用蛋白质同源建模,对其三维结构的分析发现,c.6707CT(p.Pro2236Leu)和 c.7753CT(p.Arg2585Trp)突变均会导致蛋白结构的改变。最后根据ACMG对序列变异致病性的指导原则和标准,结合已有的证据,对24种突变做了致病等级划分。结果发现,其中7个突变为可致病的突变,4种为无义突变,3种为剪接突变。7个意义未明的突变的错义突变,而其他10种错义突变则为良性或可能良性的突变。通过本研究的结果可以看出,在中国西北地区CH患者中,TG基因的突变频率为23%,其中杂合突变86.7%,复合杂合突变13.3%。两个复合杂合突变除c.7182CG/c.3035CT和c.2560CT/c.1919AG外均为重度CH患者且伴有甲状腺肿,说明TG突变可能是导致这两个患者CH发生的原因。但部分未携带有TG突变的患者也表现为重度CH,因而,可能存在其他的CH相关的基因突变,需要进一步探索。总之,本研究利用高通量测序的方法研究了西北地区CH患者的TG基因的突变,扩大了TG基因的突变谱,同时,初步确立了部分TG突变与临床表型的关系,对进一步研究CH的致病机制有重要的价值。
[Abstract]:Congenital hypothyroidism is a common endocrine disease in infants. Previous studies have found that mutations in many genes associated with thyroxine synthesis are associated with the development of Ch. Thyroglobulin gene (TGG) is the matrix for thyroid hormone synthesis. In previous studies, TG mutation affected the synthesis and secretion of thyroxine, which was one of the important causes of Ch. 130 Ch patients from Xi'an and 100 healthy individuals were studied in this study. The exon of TG gene in Ch patients was detected by high-throughput sequencing. The mutation sites of TG gene were screened, and the molecular mechanism of TG gene mutation in Ch was analyzed in 130 patients with Ch by studying the mutation spectrum of TG in Northwest China population, and analyzing the molecular mechanism of TG gene mutation in the pathogenesis of Ch. A total of 24 TG mutations, including 3 splicing mutations and 17 missense mutations, were found to cause Ch. Including c.4641delGng c.2060delGngc28642864delAn c.684040C 6843delTTGTnc. 31392TCU c.3634-ldelGnc1514GAc.7182CG. the predicted results of computational biology indicate that 12 mutants are harmful mutations, 12 are benign mutations, and the TG proteins of human beings are compared with those of cattle, pigs, orangutans, orangutans and rats, and the results of the prediction of computational biology indicate that 12 of them are benign mutations, and the TG proteins of human beings are compared with those of cattle, pigs, orangutans, orangutans and rats. It was found that the mutant p.Arg1202Cysn p.Pro2236Leuanp.Ile2394Metp.Arg2585Trp was in the conserved region of TG, while the amino acid at 2236H2394C 2585 was located in the functional domain of TG protein. It was found that the mutation of C. 6707CTp.Pro2236Leu and c.7753CTU p.Arg2585Trp) would result in the change of protein structure. Finally, according to the guidelines and criteria of ACMG for the pathogenicity of sequence variation, combined with the existing evidence, The pathogenicity grades of 24 mutations were classified. The results showed that 7 mutations were pathogenicity, 4 were nonsense mutations, 3 were splicing mutations, and 7 were undefined missense mutations. The other 10 missense mutations are benign or possibly benign. The mutation frequency of triglyceride gene in Ch patients in Northwest China was 23. The heterozygosity mutation was 86. 7% and the complex heterozygosity mutation was 13. 3%. The two complex heterozygous mutations, except c.7182CG/c.3035CT and c.2560CT/c.1919AG, were both severe Ch patients and accompanied with goiter. This indicates that TG mutation may be the cause of Ch in these two patients. However, some patients without TG mutation also present severe CH.Therefore, there may be other CH-related gene mutations that need further exploration. In this study, high-throughput sequencing was used to study the mutation of TG gene in Ch patients in Northwest China, and to enlarge the mutation spectrum of TG gene. At the same time, the relationship between some TG mutations and clinical phenotypes was preliminarily established. It is of great value to further study the pathogenesis of Ch.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R725.8

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