甲状腺过氧化物酶基因c.2268dupT突变与甲状腺结节的相关性研究

目的 探讨先天性甲状腺功能减退症(先天性甲减)患者及其家系成员发生甲状腺结节与突变位点的关系.方法 58例先天性甲减患者入选,提取外周血白细胞基因组DNA,根据甲状腺功能及超声检查结果选择靶基因.PCR扩增甲状腺过氧化物酶(TPO)、双氧化酶2(DOUX2)、双氧化酶成熟因子2(DOUXA2)、促甲状腺激素受体(TSHR)、钠/碘协同转运体(NIS)基因的所有外显子,对纯化PCR产物进行测序.发现突变后对其家系成员进行筛查.患者及家系成员行甲状腺功能和99mTc甲状腺扫描或超声检查,然后分析5个基因的突变位点与甲状腺结节的关系.结果 16例先证者为复合杂合子或纯合子,其中10例为TPO基因突变,含c.2268dupT突变者6例.37例家系成员为杂合突变,其中TPO基因突变25例.TPO基因c.2268dupT突变先证者及杂合携带者共20例,其中12例并发甲状腺结节.与其他所有突变位点组相比,c.2268dupT突变组的甲状腺结节患病率较高,差异有统计学意义(x2=13.545,P ＜0.01).结论 TPO基因c.2268dupT突变为高频突变,该突变携带者发生甲状腺结节危险性较高.     

小儿先天性甲状腺功能减退症99mTc甲状腺显像的临床意义

43例先天性甲状腺功能减退症(CH)患儿以左旋甲状腺素钠治疗至2-3周岁,暂停药4周行99mTcO-4甲状腺显像.结果 示甲状腺发育不良37例(86.05%),99mTcO-4甲状腺显像正常6例(13.95%).99mTcO-4甲状腺显像对CH的病因诊断、治疗方案选择有指导作用.

Abstract：

Forty-three children with congenital hypothyroidism(CH)underwent 99mTc thyroid scintigraphy, after being followed up by receiving levothyroxine till 2 to 3 years of age. The results showed that thyroid agenesia happened in 37 cases( 86.05% ) while entopic gland in 6 cases (13.95% ). Thyroid scintigraphy with 99mTc is an informative procedure in determining etiology and treatment schedules for children with CH.     

家族性高胆固醇血症基因突变及临床表型研究

目的 筛查家族性高胆同醇血症家系载脂蛋白(Apo)B100基因及低密度脂蛋白受体(LDLR)基因突变,并探讨其临床表现.方法 采用PCR扩增ApoB100基因包含3500、3501、3531和3480位点的序列;扩增LDLR启动子和全部18个外显子片段,产物电泳鉴定后直接序列分析,结果 与GenBank公布的基因正常序列比对,找出突变.结果 该家系LDLR基因第10外显子的第1581位碱基发生G＞A突变,导致G496E突变;未检出ApoB100基因突变.结论 此突变为一新突变,为该家系致病性突变.

Abstract：

Objective To investigate the low density lipoprotein receptor (LDLR)gene and apolipoprotein (Apo) B gene mutation in a Chinese family with familial hypercholesterolemia(FH) and give the kindrids clinical check-ups. Methods After physical examination, the kindreds underwent ECG and ultrasound checks. Blood samples were tested for lipid profiles. The promoter and all eighteen exons of LDLR gene were investigated by using PCR and agarose gel electrophoresis in combination with DNA sequence analysis. The results were compared with the normal sequences in GenBank and FH database ( www. ucl. ac. uk/fh ) to find mutations. In addition, the apolipoprotein B100 gene for known mutations (R3500Q,R3531C,R3501W and R3480W)that cause familial defective ApoB100 (FDB)was also tested using the same method. Results A novel homozygous G ＞ A mutation at the 1581 bp of exon 10 was detected in the proband and his siblings. It caused a substitution of amimo acid Glu to Gly at codon 496. A novel heterozygous G ＞A mutation at the 1581 bp of exon 10 was detected in his parents. No mutations of R3500Q,R3531C,R3501W and R3480W of ApoB100 were observed. ECGs were normal. Atherosclerosis were found in all family members by ultrasound checks. Conclusions The homozygous G ＞ A mutation at the 1581 bp of exon 10 was first determined in our country. The change of amino acid Glu to Gly is responsible for FH of the family. The type of the gene mutation was not found in the FH database( www. ucl.ac. uk/ih). It's a new type of LDLR mutation.     

DAX-1基因新的移码突变导致一例迟发型先天性肾上腺发育不良症

本研究发现1例先天性肾上腺发育不良症和低促性腺激素性性腺功能减退症患者DAX-1基因第一外显子处993delC新型移码突变,导致终止密码子提前59个氨基酸出现,其母亲、大姐及二姐均为杂合突变,父亲及哥哥为正常野生型.患者糖皮质激素替代治疗后,症状改善,但ACTH未被抑制.

Abstract：

A novel hemizygous frameshift mutation in exon1of DAX-1 gene (993delC) was found in a patient with late-onset adrenal hypoplasia congenita and hypogonadotropic hypogonadism.This mutation led the stop codon to appear in advance of 59 amino acids.His mother and two sisters were the carriers of this hemizygous mutation while his father and brother were wild-type.After glucocorticoid hormone replacement therapy, the clinical symptom was improved, but the level of ACTH was not suppressed.     

甲状腺球蛋白基因多态性与甲状腺球蛋白抗体的相关性

分析陕西地区汉族自身免疫性甲状腺疾病(AITD)患者体内甲状腺球蛋白(Tg)外显子10、12及33的单核苷酸多态性与甲状腺球蛋白抗体(TgAb)产生的相关性.对222例AITD患者依据TgAb滴度进行分组,采用PCR-RFLP方法 检测甲状腺球蛋白基因外显子10、12和33的单核苷酸多态性,并对其进行单体型分析.4个位点的等位基因及基因型在TgAb阳性组和TgAb阴性组两组分布频率差异无统计学意义;但单体型分析结果提示:在TgAb阳性组中,单体型G-C-A-C所占频率明显增高(P=0.028,OR=3.34),而单体型G-C-G-C的频率明显降低(P=0.048,OR=0.62),提示单体型G-C-A-C增多与单体型 G-C-G-C 的减少可能与AITD患者体内TgAb的产生有关.甲状腺球蛋白的基因多态性可能是导致TgAb产生的重要机制之一.

Abstract：

To identify association between the presence of previously reported four single nucleotide polymorphisms(SNPs) at exon 10, 12 and 33 of thyroglobulin(Tg) gene with autoimmune thyroid disease(AITD) patients whose TgAb is positive. In this case-control association study, the Tg gene polymorphisms at exon 10, 12, and 33 were determined by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP)method in 222 patients with AITD. According to the titers of the Tg autoantibodies(TgAb) in serum, they were divided into two subgroups: TgAb positive group and TgAb negtive group. And a haplotype case-control analysis was also done in two groups.The difference of their frequencies was analyzed by Chi-square test. No differences in alleles and genotypes frequencies were observed in all patients whose TgAb iseither positive or negative(P＞0.05). But there was a significant association of G-C-A-C haplotype with the patients whose TgAb was positive(P=0.028,OR=3.34). There is association of thyroglobulin gene polymorphisms with TgAb in patients with AITD.     

家族性肥厚型心肌病MYH7基因突变的筛查与分析

目的 研究家族性肥厚型心肌病(hypertrophic cardiomyopathy,HCM)的主要致病基因β肌球蛋白重链(beta-myosin heavy chain gene,MYH7)突变,并分析基因型与表型的关系.方法 对3个HCM家系成员的MYH7基因3～23号外显子及附近上下游序列采用DHPLC及直接测序分析.结果 在其中一个家系中发现MYH7基因14号外显子中存在Thr441Met突变,该突变曾经在一莱恩远端肌病患者中发现,而在中国人中是首次发现.另外两个家系也发现有不同位点的突变.结论 MYH7基因在HCM家系中具有较高的突变率,不同突变基因型以及基因突变携带个体在临床表型上有所差异.采取基因突变检测和分析,有利于HCM家族成员的诊断、患病风险预测及疾病早期预防和治疗.

Abstract：

Objective To detect gene mutations on beta-myosin heavy chain gene MYH7 in 3 Chinese families with hypertrophic cardiomyopathy ( HCM), and to analyze the correlation between genotype and phenotype. Methods A denaturing high-performance liquid chromatography (DHPLC) and sequencing mutation screening of the exons ( exon3-23 ) coding for MYH7 gene were performed in 3 Chinese families with HCM. Results In this study, we identified several mutations in MYHT. A mutation of Thr441 Met previously reported in a patient with Laing distal myopathy was first identified in one Chinese pedigree. Conclusion This study illustrated the high frequency of mutation in MYH7 gene in Chinese HCM families. Different mutations and carriers of the MYH7 gene present phenotypic heterogeneity. Mutation screening and analysis in HCM family could therefore facilitate the early HCM diagnosis and would be helpful for the prediction, prevention and early treatment of HCM linked with MYH7 gene mutation.     

人钠/碘转运体基因G395R与先天性甲状腺功能减退症相关

先天性甲状腺功能减退症 5 2例和 10 6例健康婴幼儿 ,采用PCR RFLP技术对钠 /碘同向转运体 (hNIS)基因 3 95位点进行基因突变筛查。研究表明hNIS基因G3 95R突变可能不是青岛地区先天性甲状腺功能减退症发病的主要原因。     

DUOXA2基因与先天性甲状腺功能低下症

<正>过氧化氢产生系统,在碘的氧化、有机化、甲状腺激素合成过程中发挥着不可缺少的作用。流行病学资料,约20%先天性甲状腺功能减退症(congenital hypothyroidism,CH,先天性甲减)是因甲状腺激素(TH)合成障碍所致。其中第一步即碘的氧化,其中许多基因参与着碘的氧化过程;甲状腺过氧化物酶(TPO)基因~([1])、二元氧化酶2(DUOX2)基因~([2])、二元氧化酶成熟因子2(DUOXA2)基因~([3])等。     

Novel mutation in a Chinese patient with progressive familial intrahepatic cholestasis type 3

Genotyping is conclusive for the diagnosis of progressive familial intrahepatic cholestasis type 3(PFIC3). Here we report a Chinese patient of PFIC3 with compound mutations in the ABCB4 gene. Liver biopsy was performed on a 17-year-old male patient with intrahepatic cholestasis of unknown etiology. Liver histology findings are indicative of intrahepatic cholestasis with extensive fibrosis. Genotyping revealed c.175C>T(p.L59L) mutation in exon 4, c.504C>T(p.N168N) mutation in exon 6, c.711A>T(p.I237I) mutation in exon 8, c.874A>T(p.K292X) in exon 9 and a novel mutation, c.1804G>T(p.G602W) in exon 15. Based on these findings, the patient was diagnosed with PFIC3. The novel mutation p.G602 W in exon 15 was predicted as probably damaging by Poly Phen-2 with a score of 0.986(sensitivity: 0.54; specificity: 0.94) and was predicted to affect protein function with a SIFT score of 0.01.     

原发性甲状腺功能减退症合并垂体增生32例临床分析

目的 通过对原发性甲状腺功能减退症(甲减)合并垂体增生的临床和影像学资料的分析,了解其临床特点及甲状腺激素替代治疗后的影像学变化.方法 分析华山医院1999至2008年门诊和住院的32例甲减合并垂体增生的患者的临床表现、激素水平、影像学检查以及治疗后随访结果.结果 32例患者多为青少年,病程在半年～8年之间,除甲减的表现外,影像学上可见垂体饱满或弥漫性增大.甲状腺素替代治疗后,1～6个月后垂体可缩小至正常.结论 青少年的原发性甲减易伴垂体增生,原发性甲减所致的垂体增生在充分的甲状腺素替代治疗后可完全逆转.

Abstract：

Objective To improve the recognition of pituitary hyperplasia secondary to primary hypothyroidism by analyzing clinical and imaging data. Methods The clinical features, hormone data,imaging findings, and treatment were reviewed in 32 patients with pituitary hyperplasia secondary to primary hypothyroidism in Huashan Hospital from 1999 to 2008. Results Thirty-two patients, most juvenile,presented clinical and imaging features suggestive of functional primary pituitary adenoma. The dose of levothyroxine was increased to maintain the thyrotropin concentration at normal values. Following adequate thyroxine replacement, pituitary hyperplasia regressed on average within 6 months. Conclusions Pituitary hyperplasia secondary to primary hypothyroidism seems to be quite prevalent in children and adolescents.Complete regression will be achieved with thyroxine replacement therapy.     

High prevalence of a novel mutation (2268 insT) of the thyroid peroxidase gene in Taiwanese patients with total iodide organification defect,and evidence for a founder effect

The mutation of the thyroid peroxidase (TPO) gene that causes the total iodide organification defect (TIOD) is a common and severe condition leading to dyshormonogenesis of the thyroid gland in Caucasians. However, the role of TIOD in Chinese patients with thyroid dyshormonogenesis is unknown. In this study we followed 16 patients from 16 unrelated families in Taiwan and performed perchlorate discharge examination. Seven patients had TIOD and 2 had the partial iodine organification defect (PIOD) among the 16 families. These 9 patients underwent screening in search of TPO gene mutations. Three new mutations (2268 insT, 2243 delT, and G157C) were detected in the 7 patients with TIOD, whereas no mutation in the TPO gene was found in the 2 patients with PIOD. The 2268 insT mutation was noted to be the most common among these TIOD patients (12 of 14 studied alleles, 86%). With 3 intragenic polymorphic markers, we found that the alleles carrying the 2268 insT mutation in Taiwan Chinese TIOD patients were tightly linked to a specific haplotype. The allele frequencies of this haplotype in the 8 patients with homozygous 2268 insT (5 unrelated families, 10 studied alleles) and in 49 normal individuals (98 studied alleles) were 1.00 and 0.02, respectively (P < 0.0001). This indicates that this common novel mutation among Taiwanese patients with TIOD is due to a founder effect.     

Mutation analysis of thyroid peroxidase gene in Chinese patients with total iodide organification defect: identification of five novel mutations

Total iodide organification defect (TIOD), where the iodide in the thyroid gland cannot be oxidized and/or bound to the protein, is caused by a defect in the thyroid peroxidase (TPO) gene. Single strand conformation polymorphism analysis was used to screen for mutations in the TPO gene from five unrelated TIOD patients in Taiwan, and five novel mutations were detected. Three of these were frameshift mutations: a single T insertion between nucleotide position 2268 and 2269 (c.2268-2269 insT) in exon 13 and two single C deletions at nucleotide positions 843 (c.843 delC) and 2413 (c.2413 delC) in exon 8 and 14 respectively. The other two were single nucleotide substitutions (c.G1477>A and c.G2386>T) located in exons 9 and 13 respectively. While the former would result in amino acid substitution (Gly493Ser) in the highly conserved region of the TPO polypeptide, the latter would result in either amino acid substitution (Asp796Tyr) or alternative splicing. Of those identified TPO mutations, c.2268-2269 insT was most prevalent and was detected as heterozygous in all but one TIOD patients. All five TIOD patients investigated in this study were compound heterozygous. The method presented in this study could be used for carrier assessment and mutation analysis of newly identified TIOD patients.     

Pseudodominant inheritance of goitrous congenital hypothyroidism caused by TPO mutations: molecular and in silico studies

CONTEXT AND OBJECTIVE: Most cases of goitrous congenital hypothyroidism (CH) from thyroid dyshormonogenesis 1) follow a recessive mode of inheritance and 2) are due to mutations in the thyroid peroxidase gene (TPO). We report the genetic mechanism underlying the apparently dominant inheritance of goitrous CH in a nonconsanguineous family of French Canadian origin. DESIGN, SETTING, AND PARTICIPANTS: Two brothers identified by newborn TSH screening had severe hypothyroidism and a goiter with increased (99m)Tc uptake. The mother was euthyroid, but the father and two paternal uncles had also been diagnosed with goitrous CH. After having excluded PAX8 gene mutations, we hypothesized that the underlying defect could be TPO mutations. RESULTS: Both compound heterozygous siblings had inherited a mutant TPO allele carried by their mother (c.1496delC; p.Pro499Argfs2X), and from their father, one brother had inherited a missense mutation (c.1978C-->G; p.Gln660Glu) and the other an insertion (c.1955insT; p.Phe653Valfs15X). The thyroid gland of one uncle who is a compound heterozygote for TPO mutations (p.Phe653Valfs15X/p.Gln660Glu) was removed because of concurrent multiple endocrine neoplasia type 2A. Immunohistochemistry revealed normal TPO staining, implying that Gln660Glu TPO is expressed properly. Modeling of this mutant in silico suggests that its three-dimensional structure is conserved, whereas the electrostatic binding energy between the Gln660Glu TPO and its heme group becomes repulsive. CONCLUSION: We report a pedigree presenting with pseudodominant goitrous CH due to segregation of three different TPO mutations. Although goitrous CH generally follows a recessive mode of inheritance, the high frequency of TPO mutations carriers may lead to pseudodominant inheritance.     

Loss of heterozygocity at the thyroid peroxidase gene locus in solitary cold thyroid nodules.

Germline mutations in both alleles of the thyroid peroxidase (TPO) gene have been reported as a frequent cause of congenital hypothyroidism resulting from a total iodide organification defect (TIOD). Because TPO mutations have a prevalence of 1 in 66,000 newborns and is inherited in an autosomal recessive mode the frequency of a heterozygous germline mutation in the TPO gene should reach about 1 in 260 in the population. A somatic TPO mutation coinciding with a somatic loss of one of the TPO alleles or a TPO germline mutation could lead to somatic loss of TPO activity with impairment of thyroid hormone synthesis and decrease of growth control. The latter would lead to increased thyroid epithelial cell proliferation and the subsequent development of a scintigraphically cold thyroid nodule (CTN). To test this hypothesis we studied 40 CTN for the presence of mutations or loss of heterozygosity (LOH) in the TPO gene. For comparisons we also studied LOH in 17 autonomously functioning thyroid nodules (AFTN). Genomic DNA was extracted from nodular and surrounding tissue, polymerase chain reaction (PCR) amplified, sequenced, and analyzed for LOH. In 6 CTNs of 37 informative cases we detected LOH using the genomic markers sRA, D2S2268, and D2S319 within or near the TPO gene locus (2p24-25). In contrast, a genomic marker closer to the centromer (D2S144, 2p24-21) shows LOH in only 1 CTN. We did not detect LOH in AFTN. In none of the cases a germline or somatic mutation in the TPO gene was detectable in the TPO gene. LOH in 6 of 37 CTNs suggests that genetic defects at the TPO or the chromosomal locus 2p24-25 might play a role in the etiology of CTNs. However, we did not find the combination of LOH with a somatic mutation in the TPO gene. It is therefore likely that a gene defect near the TPO locus is part of the neoplastic process in a subgroup of CTNs.     

Two compound heterozygous mutations (c.215delA/c.2422T-->C and c.387delC/c.1159G-->A) in the thyroid peroxidase gene responsible for congenital goitre and iodide organification defect

BACKGROUND: Iodide organification defects are frequently but not always associated with mutations in the thyroid peroxidase (TPO) gene and characterized by a positive perchlorate discharge test. These mutations phenotypically produce a congenital goitrous hypothyroidism, with an autosomal recessive mode of inheritance. OBJECTIVES: In the present study we extended our initial molecular studies in six unrelated patients heterozygous for the TPO mutations, in order to identify the second mutation in this autosomal recessive disease. METHODS: The promoter and the complete coding regions of the human TPO and DUOXA2 genes, along with the flanking regions of each intron were analysed by direct DNA sequencing. RESULTS: Four different inactivating TPO mutations were identified in two patients: two novel mutations (c.215delA [p.Q72fsX86] and c.1159G-->A [p.G387R]) and two previously reported (c.387delC [p.N129fsX208] and c.2422T-->C [p.C808R]), confirming the inheritance of two different compound heterozygous mutations, c.215delA/c.2422T-->C and c.387delC/c.1159G-->A. The remaining four patients did not show additional inactivating mutations in the TPO gene and all had only the wild type sequencing in the DUOXA2 gene. CONCLUSIONS: We have reported two patients with iodide organification defect caused by two compound heterozygous mutations, c.215delA/c.2422T-->C [p.Q72fsX86/p.C808R] and c.387delC/c.1159G-->A [p.N129fsX208/p.G387R], in the TPO gene and four patients with monoallelic TPO defect. Identification of the molecular basis of this disorder might be helpful for understanding the pathophysiology of congenital hypothyroidism.     

Analysis of TPO gene in Turkish children with iodide organification defect: identification of a novel mutation

The objective was to determine molecular genetic analysis of the TPO gene in Turkish children with iodide organification defect (IOD). Patients with a diagnosis of primary hypothyroidism were evaluated. Subjects having a definite diagnosis of autoimmune thyroiditis, thyroid gland dysplasia and, or iodine deficiency were excluded. A total of 10 patients from nine unrelated Turkish families, with an unknown etiology of hypothyroidism, and with a presumptive diagnosis of IOD were included in the study. A perchlorate discharge test (PDT) was performed to all subjects, and sequence analysis of TPO gene was applied in patients with a positive PDT. Five out of 10 patients have a total IOD, while the five remaining patients have a partial IOD according to PDT results. In two sisters, one has a partial and the other one has a total IOD a novel homozygous nonsense p.Q315X mutation was found in exon 8. Additionally, a previously known homozygous missense p.R314W mutation was detected in the same exon in another patient with a total IOD. No TPO gene mutation was detected in any of the seven remaining patients. Two different TPO gene mutations were found to be responsible for IOD in two unrelated Turkish families from the same ethnic background. More subjects should be screened for detecting the prevalence and spectrum profile of TPO mutations in our population that might be helpful for understanding the pathophysiology of congenital hypothyroidism.     

Goitrous congenital hypothyroidism and hearing impairment associated with mutations in the TPO and SLC26A4/PDS genes

CONTEXT: Pendred syndrome (PS) and thyroid peroxidase (TPO) deficiency are autosomal-recessive disorders that result in thyroid dyshormonogenesis. They share congenital hypothyroidism, goiter, and an iodide organification defect as common features. Whereas the hallmark of PS is sensorineural deafness, other forms of congenital hypothyroidism may also lead to hearing impairment. Therefore, a definite diagnosis may be difficult and require molecular genetic analyses. CASE REPORT: The propositus presented at birth with primary hypothyroidism and goiter. He also had congenital bilateral moderate hearing loss, and PS was suspected. METHODS: We sequenced the SLC26A4/PDS and TPO genes in the propositus and tested familial segregation of mutations in all available family members who were phenotypically normal. The functional consequences of the identified pendrin mutation (p.R776C) were studied in vitro. RESULTS: Sequencing of the SLC26A4/PDS gene revealed a single monoallelic missense mutation in the propositus (p.R776C). This mutation, which was inherited from his unaffected mother, has previously been identified in an individual with deafness and an enlarged vestibular aqueduct. Sequencing of the TPO gene revealed compound heterozygosity for a novel nonsense mutation (p.Q235X) and a known missense mutation (p.Y453D). The mutant pendrin (p.R776C) retained its ability to transport iodide in vitro. CONCLUSIONS: These results show that the propositus carries three sequence variants in two genes: a monoallelic SLC26A4/PDS sequence variant and compound heterozygous TPO mutations. Our study illustrates that if only a single heterozygous SLC26A4/PDS mutation is found in a patient with goiter and deafness, other genetic explanations should be considered.     

Congenital goitrous hypothyroidism: mutation analysis in the thyroid peroxidase gene

Background Iodide organification defect (IOD) is characterized by a reduced ability of the thyroid gland to retain iodide resulting in hypothyroidism. Mutations in thyroid peroxidase (TPO) gene appear to be the most common cause of IOD and are commonly inherited in an autosomal recessive fashion. The TPO gene is located on the chromosome 2p25. It comprises 17 exons, covers approximately 150 kb of genomic DNA and codes 933 amino acids. Objetives In this study, we characterize the clinical and molecular basis of seven patients from four unrelated families with congenital hypothyroidism (CH) because of IOD. Design and Methods All patients underwent clinical, biochemical and imaging evaluation. The promoter and the complete coding regions of the human TPO along with the flanking intronic regions were analysed by single‐strand conformation polymorphism analysis and direct DNA sequencing. Segregation analysis of mutations was carried out, and the effect of the novel missense identified mutations was investigated by ‘in silico’ studies. Results All subjects had congenital and persistent primary hypothyroidism. Three novel mutations: c.796C>T [p.Q266X], c.1784G>A [p.R595K] and c.2000G>A [p.G667D] and a previously reported mutation: c.1186_1187insGGCC [p.R396fsX472] have been identified. Four patients were compound heterozygous for p.R396fsX472/p.R595K mutations, two patients were homozygous for p.R595K, and the remaining patient was a compound heterozygous for p.Q266X/p.G667D. Conclusions Our findings confirm the genetic heterogeneity of TPO defects and the importance of the implementation of molecular studies to determinate the aetiology of the CH with dyshormonogenesis.     

Two novel mutations in the thyroglobulin gene as cause of congenital hypothyroidism: identification a cryptic donor splice site in the exon 19

Thyroglobulin (TG) is a homodimeric glycoprotein synthesized by the thyroid gland. To date, 52 mutations of the TG gene have been identified in humans.The purpose of the present study was to identify and characterize new mutations in the TG gene. We report a French patient with congenital hypothyroidism, mild enlarged thyroid gland and low levels of serum TG. Sequencing of DNA, genotyping, expression of chimeric minigenes as well as bioinformatics analysis were performed.DNA sequencing identified the presence of compound heterozygous mutations in the TG gene: the paternal mutation consists of a c.3788-3789insT or c.3788dupT, whereas the maternal mutation consists of g.IVS19+3_+4delAT. Minigene analysis of the g.IVS19+3_+4delAT mutant showed that the exon 19 is skipped during pre-mRNA splicing or partially included by use of cryptic 5′ splice site located to 100 nucleotides downstream of the wild type exon-intron junction. The c.3788-3789insT mutation results in a putative truncated protein of 1245 amino acids, whereas g.IVS19+3_4delAT mutation originates two putative truncated proteins of 1330 and 1349 amino acids.In conclusion, we show that the g.IVS19+3_+4delAT mutation promotes the activation of a cryptic donor splice site in the exon 19 of the TG gene. These results open up new perspectives in the knowledge of the mechanism of splicing for the TG pre-mRNA.