TAF1 is needed for the proliferation and maturation of thyroid follicle cells via Notch signaling.

Thyroid dysgenesis (TD) is the common pathogenic mechanism of congenital hypothyroidism (CH). In addition, known pathogenic genes are limited to those that are directly involved in thyroid development. To identify additional candidate pathogenetic genes, we performed forward genetic screening for TD in zebrafish, followed by positional cloning. The candidate gene was confirmed in vitro using the Nthy-ori 3.1 cell line and in vivo using a zebrafish model organism. We obtained a novel zebrafish line with thyroid dysgenesis and identified the candidate pathogenetic mutation TATA-box binding protein associated Factor 1 (taf1) by positional cloning. Further molecular studies revealed that taf1 was needed for the proliferation of thyroid follicular cells by binding to the NOTCH1 promoter region. Knockdown of TAF1 impaired the proliferation and maturation of thyroid cells, thereby leading to thyroid dysplasia. This study showed that TAF1 promoted Notch signaling and that this association played a pivotal role in thyroid development.NEW & NOTEWORTHY In our study, we obtained a novel zebrafish line with thyroid dysgenesis (TD) and identified the candidate pathogenetic mutation TATA-box binding protein associated Factor 1 (taf1). Further researches revealed that taf1 was required for thyroid follicular cells by binding to the NOTCH1 promoter region. Our findings revealed a novel role of TAF1 in thyroid morphogenesis.

Pathogenic variations in MAML2 and MAMLD1 contribute to congenital hypothyroidism due to dyshormonogenesis by regulating the Notch signalling pathway.

BACKGROUND: In several countries, thyroid dyshormonogenesis is more common than thyroid dysgenesis in patients with congenital hypothyroidism (CH). However, known pathogenic genes are limited to those directly involved in hormone biosynthesis. The aetiology and pathogenesis of thyroid dyshormonogenesis remain unknown in many patients. METHODS: To identify additional candidate pathogenetic genes, we performed next-generation sequencing in 538 patients with CH and then confirmed the functions of the identified genes in vitro using HEK293T and Nthy-ori 3.1 cells, and in vivo using zebrafish and mouse model organisms. RESULTS: We identified one pathogenic MAML2 variant and two pathogenic MAMLD1 variants that downregulated canonical Notch signalling in three patients with CH. Zebrafish and mice treated with N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butylester, a γ-secretase inhibitor exhibited clinical manifestations of hypothyroidism and thyroid dyshormonogenesis. Through organoid culture of primary mouse thyroid cells and transcriptome sequencing, we demonstrated that Notch signalling within thyroid cells directly affects thyroid hormone biosynthesis rather than follicular formation. Additionally, these three variants blocked the expression of genes associated with thyroid hormone biosynthesis, which was restored by HES1 expression. The MAML2 variant exerted a dominant-negative effect on both the canonical pathway and thyroid hormone biosynthesis. MAMLD1 also regulated hormone biosynthesis through the expression of HES3, the target gene of the non-canonical pathway. CONCLUSIONS: This study identified three mastermind-like family gene variants in CH and revealed that both canonical and non-canonical Notch signalling affected thyroid hormone biosynthesis.

Insights into the pathogenesis of hereditary angioedema using genetic sequencing and recombinant protein expression analyses.

BACKGROUND: The pathogenesis of hereditary angioedema (HAE) type I and type II is linked to defective C1 esterase inhibitor (C1-INH) encoded by the SERPING1 gene. There are substantial variabilities in the clinical presentations of patients with HAE that are not directly correlated to the serum levels of C1-INH. The impact of SERPING1 variants on C1-INH expression, structure, and function is incompletely understood. OBJECTIVE: To investigate the influence of SERPING1 variants on the C1-INH expression, structure, and function of 20 patients with HAE from 14 families with no prior genetic diagnosis. METHODS: Patients underwent whole-exome sequencing (WES). If no variants were identified, whole-genome sequencing (WGS) was performed. Except for the frameshift and large deletions, each C1-INH variant was recombinantly produced and, if synthesized and secreted, was subjected to structural, oligosaccharide, and functional analyses. RESULTS: We identified 11 heterozygous variants in the SERPING1 gene, of which 5 were classified as pathogenic (E85Dfs∗63, N166Qfs∗91, K201Qfs∗56, P399A, and R466H) and 6 as variants of uncertain significance (C130W, I224S, N272del, K273del, L349F, and F471C). Three large heterozygous deletions were discovered through WGS. Our data indicate that C130W, N272del, P399A, and F471C are poorly synthesized, I224S prevents proper C1-INH folding, and K273del impairs C1-INH function by adding an additional oligosaccharide. Further evaluation suggests that compound variant P399A/L349F contributes to a more severe clinical phenotype. CONCLUSIONS: Our combined approach of WES and WGS uncovered SERPING1 gene alternations in each patient. The recombinant protein production followed by systematic antigenic, structural, and functional assessment facilitates the identification of underlying pathogenic mechanisms in HAE.

Large-scale forward genetic screening of zebrafish affecting thyroid development.

The thyroid follicular cells originate from the foregut endoderm and elucidating which genes and signaling pathways regulate their development is crucial for understanding developmental disorders as well as diseases in adulthood. We exploited unique advantages of the zebrafish model to carry an ENU-based forward mutagenesis screen aiming at identifying genes involved in the development and function of the thyroid follicular cells. ENU is an excellent chemical mutagen due to its high mutation efficiency and an indiscriminate selection of genes. A total of 1606 F2 families from 36 ENU treated founders was raised and embryos from F3 generation were collected at 5dpf to perform the whole embryo in situ hybridization with a cocktail probe of thyroid marker thyroglobulin(tg), pituitary marker thyroid stimulating hormone (tshba) to determine the mutagenic phenotype. Among the 1606 F2 families, 112 F2 mutant families with normal development stages except for thyroid dysfunction were identified and divided into three different groups according to their phenotypic characteristics. Further studies of the mutants are likely to shed more insights into the molecular basis of both the thyroid development and function in the zebrafish and vertebrate.

PARD3 gene variation as candidate cause of nonsyndromic cleft palate only.

Nonsyndromic cleft palate only (NSCP) is a common congenital malformation worldwide. In this study, we report a three-generation pedigree with NSCP following the autosomal-dominant pattern. Whole-exome sequencing and Sanger sequencing revealed that only the frameshift variant c.1012dupG [p. E338Gfs*26] in PARD3 cosegregated with the disease. In zebrafish embryos, ethmoid plate patterning defects were observed with PARD3 ortholog disruption or expression of patient-derived N-terminal truncating PARD3 (c.1012dupG), which implicated PARD3 in ethmoid plate morphogenesis. PARD3 plays vital roles in determining cellular polarity. Compared with the apical distribution of wild-type PARD3, PARD3-p. E338Gfs*26 mainly localized to the basal membrane in 3D-cultured MCF-10A epithelial cells. The interaction between PARD3-p. E338Gfs*26 and endogenous PARD3 was identified by LC-MS/MS and validated by co-IP. Immunofluorescence analysis showed that PARD3-p. E338Gfs*26 substantially altered the localization of endogenous PARD3 to the basement membrane in 3D-cultured MCF-10A cells. Furthermore, seven variants, including one nonsense variant and six missense variants, were identified in the coding region of PARD3 in sporadic cases with NSCP. Subsequent analysis showed that PARD3-p. R133*, like the insertion variant of c.1012dupG, also changed the localization of endogenous full-length PARD3 and that its expression induced abnormal ethmoid plate morphogenesis in zebrafish. Based on these data, we reveal PARD3 gene variation as a novel candidate cause of nonsyndromic cleft palate only.

The mutation screening in candidate genes related to thyroid dysgenesis by targeted next-generation sequencing panel in the Chinese congenital hypothyroidism.

OBJECTIVE: Congenital hypothyroidism (CH) is known to be due to thyroid dyshormonogenesis (DH), which is mostly inherited in an autosomal recessive inheritance pattern or thyroid dysgenesis (TD), whose inheritance pattern is controversial and whose molecular etiology remains poorly understood. DESIGN AND METHODS: The variants in 37 candidate genes of CH, including 25 genes related to TD, were screened by targeted exon sequencing in 205 Chinese patients whose CH cannot be explained by biallelic variants in genes related to DH. The inheritance pattern of the genes was analyzed in family trios or quartets. RESULTS: Of the 205 patients, 83 patients carried at least one variant in 19 genes related to TD, and 59 of those 83 patients harbored more than two variants in distinct candidate genes for CH. Biallelic or de novo variants in the genes related to TD in Chinese patients are rare. We also found nine probands carried only one heterozygous variant in the genes related to TD that were inherited from a euthyroid either paternal or maternal parent. These findings did not support the monogenic inheritance pattern of the genes related to TD in CH patients. Notably, in family trio or quartet analysis, of 36 patients carrying more than two variants in distinct genes, 24 patients carried these variants inherited from both their parents, which indicated that the oligogenic inheritance pattern of the genes related to TD should be considered in CH. CONCLUSIONS: Our study expanded the variant spectrum of the genes related to TD in Chinese CH patients. It is rare that CH in Chinese patients could be explained by monogenic germline variants in genes related to TD. The hypothesis of an oligogenic origin of the CH should be considered.

Tpo knockout in zebrafish partially recapitulates clinical manifestations of congenital hypothyroidism and reveals the involvement of TH in proper development of glucose homeostasis.

Congenital hypothyroidism (CH) is a highly prevalent but treatable neonatal endocrine disorder. Thyroid peroxidase (TPO) catalyzes key reactions in thyroid hormone (TH) synthesis. TPO mutations have been found to underlie approximately 5% of congenital hypothyroidism in Chinese patients with more severe phenotypes, the treatment of whom usually requires a higher dose of L-thyroxine. The Tpo gene of zebrafish has 66% homology with the human TPO gene, and synteny analysis has indicated that it is likely a human TPO ortholog. In this study, we generated a tpo-/- mutant zebrafish line through knockout of tpo with CRISPR/Cas9 and investigated the associated phenotypes. Tpo-/- mutant zebrafish displayed growth retardation; an increased number of thyroid follicular cells; and abnormal extrathyroidal phenotypes including pigmentation defects, erythema in the thoracic region, delayed scale development and failure of swim bladder secondary lobe formation. All these abnormal phenotypes were reversed by 30 nM thyroxine (T4) treatment starting at 1 month of age. Tpo-/- mutants also showed increased glucose levels during larval stages, and the increases were induced at least in part by increasing glucagon and decreasing insulin expression. Our work indicates that tpo-mutant zebrafish may serve as a human congenital hypothyroidism model for studying TPO- and TH-related disease mechanisms.

Upregulation of GBP1 in thyroid primordium is required for developmental thyroid morphogenesis.

PURPOSE: Congenital hypothyroidism (CH) is a common congenital endocrine disorder in humans. CH-related diseases such as athyreosis, thyroid ectopy, and hypoplasia are primarily caused by dysgenic thyroid development. However, the underlying molecular mechanisms remain unknown. METHODS: To identify novel CH candidate genes, 192 CH patients were enrolled, and target sequencing of 21 known CH-related genes was performed. The remaining 98 CH patients carrying no known genes were subjected to exome sequencing (ES). The functions of the identified variants were confirmed using thyroid epithelial cells in vitro and in zebrafish model organisms in vivo. RESULTS: Four pathogenic GBP1 variations from three patients were identified. In zebrafish embryos, gbp1 knockdown caused defective thyroid primordium morphogenesis and hypothyroidism. The thyroid cells were stuck together and failed to dissociate from each other to form individual follicles in gbp1-deficient embryos. Furthermore, defects were restored with wild-type human GBP1 (hGBP1) messenger RNA (mRNA) except for mutated hGBP1 (p.H150Y, p.L187P) overexpression. GBP1 promoted ß-catenin translocation into the cytosol and suppressed the formation of cellular adhesion complexes. Suppression of cell-cell adhesion restored the thyroid primordium growth defect observed in gbp1-deficient zebrafish embryos. CONCLUSION: This study provides further understanding regarding thyroid development and shows that defective cellular remodeling could cause congenital hypothyroidism.

Correlation of DUOX2 residual enzymatic activity with phenotype in congenital hypothyroidism caused by biallelic DUOX2 defects.

DUOX2 is the most frequently mutated gene in patients with congenital hypothyroidism (CH) in China. However, no reliable genotype-phenotype relationship has been found in patients with DUOX2 mutations. In this study, DUOX2 mutations were screened in 266 CH patients, and the enzymatic activity of 89 DUOX2 variants was determined in vitro. Furthermore, the DUOX2 residual activity in 76 CH patients caused by DUOX2 biallelic mutations was calculated. The thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels were found to be higher and lower in patients with DUOX2 residual activity ≤22%, respectively, compared to patients with residual enzymatic activity >22%. Moreover, we interpreted the pathogenicity of DUOX2 variants by applying the ACMG classification criteria with or without PS3/BS3 evidence. The results indicated that residual DUOX2 enzymatic activity was closely related to the clinical phenotypes of CH patients caused by DUOX2 biallelic mutations. These findings suggest that the residual enzymatic activity of 22% may be a cutoff value for estimating the severity of hypothyroidism in CH patients with biallelic DUOX2 mutations. Well-established functional studies are useful and necessary to evaluate the pathogenicity of DUOX2 variants, improving the accuracy and scope of genetic consultations.

The effect of radioiodine treatment on the characteristics of TRAb in Graves' disease.

BACKGROUND: Graves' disease (GD) is one of the most common autoimmune thyroid diseases (AITDs) in humans, and thyrotropin receptor antibody (TRAb) is a characterized autoantibody in GD. The use of radioactive iodine therapy (RAI) for GD treatment is increasing. OBJECTIVES: We studied the biological properties of TRAb and evaluated the effect of RAI therapy on TRAb in GD patients. METHODS: In total, 225 patients (22 onset GD patients without 131I therapy, 203 GD patients treated with 131I therapy) and 20 healthy individuals as normal controls were included in this study. Clinical assessments were performed, and we examined in vitro the biological properties of TRAb in the 22 onset GD patients and 20 controls as well as 84 GD patients with 131I therapy. RESULTS: Serum TRAb and thyroid peroxidase antibody (TPOAb) levels increased in the initial year of RAI treatment, and both antibodies decreased gradually after one year. After 5 years from radioiodine treatment, TRAb and TPOAb levels decreased in 88% and 65% of GD patients, respectively. The proportion of patients positive for thyroid-stimulatory antibody (TSAb) was significantly higher in the 7-12-month group, and thyroid-blocking antibody (TBAb) levels were elevated after one year in half of the patients who received 131I treatment. CONCLUSIONS: Treatment of GD patients with radioiodine increased TPOAb and TRAb (their main biological properties were TSAbs) within the first year after therapy, and the main biological properties of elevated TRAb were TBAbs after 1 year.

A five-gene panel refines differential diagnosis of thyroid nodules.

BACKGROUND: Molecular testing for oncogenic mutations in fine-needle aspiration has showed high predictive value in identifying malignant lesions from thyroid nodules with indeterminate cytology. METHODS: To figure out an efficient and economical gene panel for most medical institutions in China, we designed a five-gene panel including BRAF/NRAS/KRAS/HRAS/TERT genes and conducted a retrospective study to evaluate the role of this five-gene diagnostic panel in differential diagnosis of thyroid nodules. RESULTS: A total of 665 patients with 695 thyroid nodules were investigated in the current study. The fine-needle aspiration biopsy and surgically separated thyroid tissue specimens were harvested to test BRAF, TERT, NRAS, KRAS, and HRAS mutations. We identified 261 mutations in 665 patients, including 177 V600E mutations in BRAF. Three hundred and sixty-nine patients who underwent thyroid surgery after completion of the initial clinical and cytological evaluation were enrolled in the final analysis. The diagnostic sensitivity, specificity, and accuracy of the combination of FNAB cytology and five-gene detection were 74.7%, 93.8%, and 84.8%, respectively. BRAF V600E and five-gene panel could recognize 46.4% and 53.6% of papillary thyroid carcinoma in the patients with cytologically indeterminate nodules. CONCLUSION: The five-gene panel can effectively improve the sensitivity, negative predictive value, and accuracy of fine-needle aspiration biopsy cytology, especially in the patients with cytologically indeterminate nodules.

Next-generation sequencing reveals genetic landscape in 46, XY disorders of sexual development patients with variable phenotypes.

Disorders of sexual development (DSD) are rare congenital conditions in which chromosomal, gonadal, or anatomical sex is atypical. Currently, less than 20% of patients receive an accurate genetic diagnosis. Targeted next-generation sequencing, consisting of 33 candidate genes and 47 genes involved in sexual differentiation and development, was performed on 70 46, XY DSD patients. Functional assays were performed to evaluate the expression and transcriptional activity of one reported and nine novel mutations of NR5A1. In total, 113 mutations, including 86 novel and 27 reported sites in 40 genes, were identified in 52 patients. Among them, 37 mutations from 19 genes were first identified in 46, XY DSD patients, including EGF, LHX9, and CST9. Nine patients displayed biallelic mutations, 12 had mutations in sex chromosome genes and 14 had monoallelic mutations in NR5A1, BMP4, and WT1. Higher frequency mutations were identified in AR, SRD5A2, and NR5A1. Six missense, one frameshift, and one three-nucleotide deletion mutations of NR5A1 were shown to impair the transactivation ability with an altered nuclear aggregation of p.T29K and p.N44del variants. Multiple genetic mutations were identified in 33 of the 70 patients. The targeted sequencing panel provides an efficient method for the etiological diagnosis of 46, XY DSD patients and expands the candidate genes and inherited patterns.

A dense mapping study of six European AITD susceptibility regions in a large Chinese Han Cohort of Graves' disease.

OBJECTIVE: We aimed to investigate the six susceptibility loci of GD identified from European population in Chinese Han population and further to estimate the genetic heterogeneity of them in stratification of our GD patients. DESIGN: Dense mapping studies based on GWAS. PATIENTS: A total of 1536 GD patients and 1516 controls in GWAS stage and 1994 GD patients and 2085 controls and 5033 GD patients and 5389 controls in two replication stages. MEASUREMENTS: Based on our previous GWAS data, independently GD-associated SNPs in each region were identified by TagSNP analysis and logistic regression analysis. The association of these SNPs was investigated in 1994 GD patients and 2085 controls, and then, the significantly associated SNPs (P < 0.05) were further genotyped in a second cohort including 5033 GD patients and 5389 controls. RESULTS: After the first replication stage, four SNPs from three regions with Pfirst  < 0.05 were further selected and genotyped in another independent cohort. The association of two SNPs with GD was confirmed in combined Chinese cohorts: rs12575636 at 11q21 (Pcombined  = 7.55 × 10-11 , OR = 1.27) and rs1881145 in TRIB2 at 2p25.1 (Pcombined  = 5.59 × 10-8 , OR = 1.14). Further study disclosed no significant difference for these SNPs between GD subsets. However, eQTL data revealed that SESN3 could be a potential susceptibility gene of GD in 11q21 region. CONCLUSIONS: Out of the six susceptibility loci of GD identified from European population, two risk loci were confirmed in a large Chinese Han population. There is variability in GD genetic susceptibility in different ethnic groups. SESN3 is a potential susceptible gene of GD in 11q21.

Multiregion sequencing reveals the intratumor heterogeneity of driver mutations in TP53-driven non-small cell lung cancer.

Intratumor heterogeneity (ITH) in non-small cell lung cancer (NSCLC) may account for resistance after a period of targeted therapies because drugs destroy only a portion of tumor cells. The recognition of ITH helps identify high-risk patients to make effective treatment decisions. However, ITH studies are confounded by interpatient heterogeneity in NSCLC and a large amount of passenger mutations. To address these issues, we recruited NSCLC patients carrying TP53 mutations and selected driver mutations within recurrently mutated genes in NSCLC. A total of 12-paired normal-tumor tissues were subjected to whole-genome/whole-exome sequencing. From these, 367 non-silent mutations were selected as driver mutations and deeply sequenced in 61 intratumoral microdissections. We identified a universal prevalence of heterogeneity in all 12 tumors, indicating branched evolution. Although TP53 mutations were observed in single biopsy of all 12 tumors, most tumors consist of both TP53 mutated and non-mutated cells in separate regions within the same tumor. This suggests the late molecular timing of the acquisition of TP53 mutations; therefore, the detection of TP53 mutations in a single biopsy may simply not reflect the early malignant potential. In addition, we identified regions of loss of heterozygosity surrounding TP53 and CDKN2A mutations in tumor 711, which also exhibited heterogeneity in different regional samples. Because the ITH of driver mutations likely has clinical consequences, further efforts are needed to limit the impact of ITH and to improve therapeutic efficiency, which will benefit NSCLC patients receiving targeted treatments.

Effects of Osteoglycin (OGN) on treating senile osteoporosis by regulating MSCs.

BACKGROUND: Significant amount of bone mass is lost during the process of aging due to an imbalance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption in bone marrow microenvironment, which leads to net bone loss in the aging population, resulting in the pathogenesis of osteoporosis. METHODS: Firstly, differences in proliferative capacity of adipocyte or adipogenic differentiation in mouse mesenchymal stem cells (MMSCs) and senile mouse model-derived bone marrow mesenchymal stem cells (SMMSCs), as well as mRNA expression of OGN and PPARγ2 were observed. Secondly, osteogenic abilities of MMSCs and SMMSCs treated with rosiglitazone (a PPARγ2 agonist) to induce osteogenic changes were observed, and negative correlation of PPARγ2 with OGN was evaluated. Thirdly, the role of SMMSCs in promoting osteogenesis was examined through enhancing expression of OGN; besides, the related mechanism was investigated by means of expression of related adipocyte and osteoblast specific genes. RESULTS: Forced OGN expression by OGN-infected lentivirus could increase expression of Wnt5b, RUNX2, OCN, ALP and Colla1, as well as bone formation, while decreases expression of adipogenesis marker PPARγ2. It resulted in expression inhibition of adipocyte genes such as adipocytic differentiation related genes adipocyte binding protein 2 (aP2) and osteoclast differentiation factor Rankl in bone marrow, giving rise to increased bone mass. CONCLUSION: OGN may plays a significant role in osteoporosis, which may also provide a potential target for therapeutic intervention of senile osteoporosis characterized by altered differentiation of BMSCs into osteoblasts and adipocytes.

Genome-wide association study identifies a novel susceptibility gene for serum TSH levels in Chinese populations.

Thyroid-stimulating hormone (TSH) is a sensitive indicator of thyroid function. High and low TSH levels reflect hypothyroidism and hyperthyroidism, respectively. Even within the normal range, small differences in TSH levels, on the order of 0.5-1.0 mU/l, are associated with significant differences in blood pressure, BMI, dyslipidemia, risk of atrial fibrillation and atherosclerosis. Most of the variance in TSH levels is thought to be genetically influenced. We conducted a genome-wide association study of TSH levels in 1346 Chinese Han individuals. In the replication study, we genotyped four candidate SNPs with the top association signals in an independent isolated Chinese She cohort (n = 3235). We identified a novel serum TSH susceptibility locus within XKR4 at 8q12.1 (rs2622590, Pcombined = 2.21 × 10(-10)), and we confirmed two previously reported TSH susceptibility loci near FOXE1 at 9q22.33 and near CAPZB at 1p36.13, respectively. The rs2622590_T allele at XKR4 and the rs925489_C allele near FOXE1 were correlated with low TSH levels and were found to be nominally associated to patients with papillary thyroid carcinoma (PTC) (OR = 1.41, P= 0.014 for rs2622590_T, and OR = 1.61, P= 0.030 for rs925489_C). The rs2622590 and rs925489 genotypes were also correlated with the expression levels of FOXE1 and XKR4, respectively, in PTC tissues (P = 2.41 × 10(-4) and P= 0.02). Our findings suggest that the SNPs in XKR4 and near FOXE1 are involved in the regulation of TSH levels.

Robust evidence for five new Graves' disease risk loci from a staged genome-wide association analysis.

Graves' disease (GD), characterized by autoantibodies targeting antigens specifically expressed in thyroid tissues causing hyperthyroidism, is triggered by a combination of genetic and environmental factors. However, only a few loci for GD risk were confirmed in the various ethnic groups, and additional genetic determinants have to be detected. In this study, we carried out a three-stage study in 9529 patients with GD and 9984 controls to identify new risk loci for GD and found genome-wide significant associations in the overall populations for five novel susceptibility loci: the GPR174-ITM2A at Xq21.1, C1QTNF6-RAC2 at 22q12.3-13.1, SLAMF6 at 1q23.2, ABO at 9q34.2 and an intergenic region harboring two non-coding RNAs at 14q32.2 and one previous indefinite locus, TG at 8q24.22 (Pcombined < 5 × 10(-8)). The genotypes of corresponding variants at 14q32.2 and 8q24.22 were correlated with the expression levels of C14orf64 and a TG transcript skipping exon 46, respectively. This study increased the number of GD loci with compelling evidence and indicated that non-coding RNAs might be potentially involved in the pathogenesis of GD.

Identification of BACH2 as a susceptibility gene for Graves' disease in the Chinese Han population based on a three-stage genome-wide association study.

The BACH2 gene regulates B cell differentiation and function and has been reported to be a shared susceptibility gene for several autoimmune diseases. Our previous genome-wide association study (GWAS) indicated that several single nucleotide polymorphisms (SNPs) in the BACH2 gene are associated with Graves' disease (GD) in the Chinese Han population; however, the association did not achieve genome-wide significance levels. Recently, this association of BACH2 with GD was confirmed in Caucasians in the UK population, but fine mapping in this region has not yet been reported. Here, we provide a refined analysis of a 331-kb region in the BACH2 gene, which harbors 359 SNPs, using GWAS data from 1,442 GD patients and 1,468 controls. The SNPs rs2474619 and rs9344996 were implied as the independent variants associated with GD by forward and two-locus logistic regression analysis. We genotyped eight out of 10 tagSNPs with P < 1 × 10(-3) in 3,508 GD patients and 3,209 controls, the results also showed that rs2474619 was independently associated with GD in the combined population from GWAS and the second stage (P = 1.81 × 10(-5)). The rs2474619 and rs9344996 were further genotyped in the third stage cohorts, and rs2474619 showed evidence of association with GD at genome-wide significance levels in the combined population (P = 3.28 × 10(-8), odds ratio = 1.13). The association of rs9344996 with GD can be explained by its linkage to rs2474619 in the combined population. Our study clearly demonstrated that BACH2 is a susceptibility gene for GD in the Chinese Han population and further supported rs2474619, in intron 2 of BACH2, is the best association signal with GD. However, the mechanism by which BACH2 confers increased risk of GD requires further study.

Phenotypic and molecular characteristics in eleven Chinese patients with 5α-reductase Type 2 deficiency.

CONTEXT: Steroid 5α-reductase type 2 deficiency (5α-RD2) is a male-limited, autosomal recessive inherited disease. Affected 46, XY individuals usually present with ambiguous genitalia at birth. An early and precise diagnosis is of great value to the long-term prognosis of the disease. OBJECTIVE: To describe the clinical features and molecular determinants in 11 Chinese patients with the SRD5A2 gene mutation and to investigate the functional alteration arising from a novel splicing site mutation identified in one of the patients. SUBJECTS AND METHODS: Eleven subjects born with abnormal external genitalia from 10 unrelated families were recruited. Among them, nine patients who were reared as girls underwent virilization and gender change after puberty. Genotyping analysis of the SRD5A2 gene was performed in each of the patients. Haplotype analysis was performed in five patients with a prevalent mutation of p.G203S to illustrate the founder effect in China. Functional impairment of the new variant was explored by an in vitro splicing study and enzymatic activity assay. RESULTS: Nine mutations in the SRD5A2 gene were detected in the eleven patients. In addition to the previously reported p.G203S, p.R227Q, p.N193S, p.R246Q, p.Q6X, p.A228V, c.655delT and IVS1-2 A>G, a novel splicing site mutation (IVS4 + 2 T>C) was identified. From an in vitro functional study, this mutation was found to result in a skipping of exon 4 in the course of mRNA splicing, leading to a truncated protein of 205 amino acids that lacks the catalysing activity. Two siblings with the same compound heterozygous mutation (IVS1-2A>G/p.G203S) exhibited differing phenotypes and opposite patterns of gender rearing. A prevalent variation p.V89L combined with c.655delT was revealed to cause a mild phenotype of 5α-RD2 with a micropenis. CONCLUSION: This cohort study describes the phenotypic, biochemical and long-term outcome in 11 Chinese patients with 5α-RD2 deficiency and defines the genotypic spectrum of SRD5A2 mutations in China.

TSHR Variant Screening and Phenotype Analysis in 367 Chinese Patients With Congenital Hypothyroidism.

Background: Genetic defects in the human thyroid-stimulating hormone (TSH) receptor (TSHR) gene can cause congenital hypothyroidism (CH). However, the biological functions and comprehensive genotype-phenotype relationships for most TSHR variants associated with CH remain unexplored. We aimed to identify TSHR variants in Chinese patients with CH, analyze the functions of the variants, and explore the relationships between TSHR genotypes and clinical phenotypes. Methods: In total, 367 patients with CH were recruited for TSHR variant screening using whole-exome sequencing. The effects of the variants were evaluated by in-silico programs such as SIFT and polyphen2. Furthermore, these variants were transfected into 293T cells to detect their Gs/cyclic AMP and Gq/11 signaling activity. Results: Among the 367 patients with CH, 17 TSHR variants, including three novel variants, were identified in 45 patients, and 18 patients carried biallelic TSHR variants. In vitro experiments showed that 10 variants were associated with Gs/cyclic AMP and Gq/11 signaling pathway impairment to varying degrees. Patients with TSHR biallelic variants had lower serum TSH levels and higher free triiodothyronine and thyroxine levels at diagnosis than those with DUOX2 biallelic variants. Conclusions: We found a high frequency of TSHR variants in Chinese patients with CH (12.3%), and 4.9% of cases were caused by TSHR biallelic variants. Ten variants were identified as loss-of-function variants. The data suggest that the clinical phenotype of CH patients caused by TSHR biallelic variants is relatively mild. Our study expands the TSHR variant spectrum and provides further evidence for the elucidation of the genetic etiology of CH.