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Thyroid hemiagenesis (THA) is an inborn absence of one thyroid lobe of largely unknown etiopathogenesis. The aim of the study was to reveal genetic factors responsible for thyroid maldevelopment in two siblings with THA. None of the family members presented with congenital heart defect. The samples were subjected to whole-exome sequencing (WES) (Illumina, TruSeq Exome Enrichment Kit, San Diego, CA 92121, USA). An ultra-rare variant c.839C>T (p.Pro280Leu) in NKX2-5 gene (NM_004387.4) was identified in both affected children and an unaffected father. In the mother, the variant was not present. This variant is reported in population databases with 0.0000655 MAF (GnomAD v3, dbSNP rs761596254). The affected amino acid position is moderately conserved (positive scores in PhyloP: 1.364 and phastCons: 0.398). Functional prediction algorithms showed deleterious impact (dbNSFP v4.1, FATHMM, SIFT) or benign (CADD, PolyPhen-2, Mutation Assessor). According to ACMG criteria, variant is classified as having uncertain clinical significance. For the first time, NKX2-5 gene variants were found in two siblings with THA, providing evidence for its potential contribution to the pathogenesis of this type of thyroid dysgenesis. The presence of the variant in an unaffected parent, carrier of p.Pro280Leu variant, suggests potential contribution of yet unidentified additional factors determining the final penetrance and expression.

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NK2 homeobox 5 (Nkx2.5), a homeobox-containing transcription factor, is associated with a spectrum of congenital heart diseases. Recently, Nkx2.5 was also found to be differentially expressed in several kinds of tumors. In colorectal cancer (CRC) tissue and cells, hypermethylation of Nkx2.5 was observed. However, the roles of Nkx2.5 in CRC cells have not been fully elucidated. In the present study, we assessed the relationship between Nkx2.5 and CRC by analyzing the expression pattern of Nkx2.5 in CRC samples and the adjacent normal colonic mucosa (NCM) samples, as well as in CRC cell lines. We found higher expression of Nkx2.5 in CRC compared with NCM samples. CRC cell lines with poorer differentiation also had higher expression of Nkx2.5. Although this expression pattern makes Nkx2.5 seem like an oncogene, in vitro and in vivo tumor suppressive effects of Nkx2.5 were detected in HCT116 cells by establishing Nkx2.5-overexpressed CRC cells. However, Nkx2.5 overexpression was incapacitated in SW480 cells. To further assess the mechanism, different expression levels and mutational status of p53 were observed in HCT116 and SW480 cells. The expression of p21WAF1/CIP1, a downstream antitumor effector of p53, in CRC cells depends on both expression level and mutational status of p53. Overexpressed Nkx2.5 could elevate the expression of p21WAF1/CIP1 only in CRC cells with wild-type p53 (HCT116), rather than in CRC cells with mutated p53 (SW480). Mechanistically, Nkx2.5 could interact with p53 and increase the transcription of p21WAF1/CIP1 without affecting the expression of p53. In conclusion, our findings demonstrate that Nkx2.5 could act as a conditional tumor suppressor gene in CRC cells with respect to the mutational status of p53. The tumor suppressive effect of Nkx2.5 could be mediated by its role as a transcriptional coactivator in wild-type p53-mediated p21WAF1/CIP1 expression.

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Aim: To analyze the association of NKX2.5 gene with congenital heart disease (CHD), and to determine if the variants rs703752, rs3729753 and rs2277923 increase the risk for developing CHD. Materials & methods: PubMed, EBSCO and Web of Science databases were screened to identify eligible studies. Through a comprehensive meta-analysis software, the association between NKX2.5 gene variants and susceptibility of CHD was calculated by pooled odd ratio (ORs) and 95% CI. Results: We observed that the allelic model of rs703752 and rs2277923 increased the risk in the overall population: OR = 1.24; 95% CI: 1.00-1.55; Z p-value = 0.049; OR = 1.18; 95% CI: 0.01-1.37; Z p-value = 0.036; respectively. Conclusion: Our results suggested that the rs703752 and rs2277923 polymorphisms of the NKX2.5 gene are associated with CHD.

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NKX-2.5 gene is responsible for cardiac development and its targeted disruption apprehends cardiac development at the linear heart tube stage. Bioinformatic analysis was employed to investigate the codon usage pattern and dN/dS of mammalian NKX-2.5 gene. The relative synonymous codon usage analysis revealed variation in codon usage and two synonymous codons namely ATA (Ile) and GTA (Val) were absent in NKX-2.5 gene across selected mammalian species suggesting that these two codons were possibly selected against during evolution. Parity rule 2 analysis of two and four fold amino acids showed CT bias whereas six-fold amino acids revealed GA bias. Neutrality analysis suggests that selection played a prominent role while mutation had a minor role. The dN/dS analysis suggests synonymous substitution played a significant role and it negatively correlated with p-distance of the gene. Purifying natural selection played a dominant role in the genetic evolution of NKX-2.5 gene in mammals.

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BACKGROUND: Tetralogy of Fallot (TOF), the most common cyanotic heart defect and one of the most common congenital heart diseases, occurs mostly sporadically and nonsyndromically. The underlying molecular genetic mechanism is not known. Therefore, the existence of mutations in the homeodomain-encoding region of NKX2.5 gene in Iranian patients with tetralogy of Fallot is evaluated. MATERIALS AND METHODS: In the present study, we analyzed the peripheral blood samples of27 patients in order to find any mutation in the 180 bp homeodomain-encoding region of NKX2.5 gene, which is known to be involved in heart development and diseases. DNA was extracted and all the samples were amplified by polymerase chain reaction (PCR) and sequenced. RESULTS: Twenty-seven patients were included in the study. Twenty-five of them were infants and children (6 days to 11 years of age), one was a teenager (14-years of age), and another was a 33-year-old man [mean ± standard deviation (SD): 5.80 ± 3.90 years]. Thirteen patents were males (mean ± SD: 6.587077 ± 5.02 years) and 14 were females (mean ± SD: 5.0726 ± 2.81 years). One synonymous variant, i.e., c.543G>A was identified in one patient. CONCLUSION: Mutations in the homeodomain-encoding region of NKX2.5 gene may not have an outstanding role in etiology of tetralogy of Fallot patients in Iran.

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Congenital heart defects (CHDs) represent the biggest fraction of morbid congenital anomalies worldwide. Owing to their complex inheritance patterns and multifactorial etiologies, these defects are difficult to identify before complete manifestation. Research over the past two decades has established firmly the role of genetics in the development of these congenital defects. While syndromic CHDs are more straightforward, non-syndromic CHDs are usually characterized by multiple mutations that affect intricate inter-connected developmental pathways. Knock-out and gene expression studies in mice and other genetic models have been performed to elucidate the roles of these implicated genes. Functional analysis has not been able to resolve the complete picture, as increasingly more downstream effects are continuously being assigned to CHD mutant factors. NKX2-5, a cardiac transcription factor, has received much attention for its role in cardiac dysmorphogenesis. Approximately 50 different mutations in this gene have been identified to date, and only a few have been functionally characterized. The mutant NKX2-5 factor can regulate a number of off-targets downstream to facilitate CHD development. This review summarizes the genetic etiology of congenital heart defects and emphasizes the need for NKX2-5 mutation screening.

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Congenital heart disease (CHD) is the most common birth abnormality, and more than 40% CHD subtypes are sporadic atrial septal defect (ASD) and ventricular septal defect (VSD). The etiology of ASD and VSD remains largely unknown. NKX2-5 gene is a highly conserved homeobox protein gene and expressed in the developing heart. Its mutations can cause sporadic ASD and VSD. This study aimed to investigate the genetic variations of NKX2-5 in ASD and VSD in Chinese Yunnan population. The whole 2 coding exon and partial flanking intron sequences of NKX2-5 gene were screened using DNA sequencing in 107 ASD patients and 391 VSD patients as well as 487 healthy individuals (control) who had parental origin (three generations) from the Yunnan province in China. Results found that, 4 reported single nucleotide polymorphisms (SNPs) (rs2277923, rs3729753, rs703752 and rs202071628) were detected. A novel heterozygous DNA sequence variant (DSV) (1500G>C) in the 3'UTR region of NKX2-5 gene were identified in 2 VSD patients, but none in ASD and controls. One single nucleotide polymorphism (rs2277923), the frequency of which was significantly higher in ASD group, and the allele and genotype were associated with the occurrence of ASD. Besides, a weak statistical association existed between rs703752 and VSD (uncorrected P=0.028). The novel DSV (1500G>C) of NKX2-5 gene may contribute to a small number of VSD, and rs2277923 SNP may contribute to the risk of sporadic ASD in Chinese Yunnan population.

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The Holt-Oram syndrome (HOS) is an autosomal dominant condition characterized by upper limb and cardiac malformations. Mutations in the TBX5 gene cause HOS and have also been associated with isolated heart and arm defects. Interactions between the TBX5, GATA4 and NKX2.5 proteins have been reported in humans. We screened the TBX5, GATA4, and NKX2.5 genes for mutations, by direct sequencing, in 32 unrelated patients presenting classical (8) or atypical HOS (1), isolated congenital heart defects (16) or isolated upper-limb malformations (7). Pathogenic mutations in the TBX5 gene were found in four HOS patients, including two new mutations (c.374delG; c.678G > T) in typical patients, and the hotspot mutation c.835C > T in two patients, one of them with an atypical HOS phenotype involving lower-limb malformations. Two new mutations in the GATA4 gene were found in association with isolated upper-limb malformations, but their clinical significance remains to be established. A previously described possibly pathogenic mutation in the NKX2.5 gene (c.73C > 7) was detected in a patient with isolated heart malformations and also in his clinically normal father.

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Objective To identify the rale of NKX2-5 gene in cardiomyocyte differentiation and its mechanism.Methods P19 cells were divided into transfected and non-transfected groups.In the transfected group,P19 cells were with stable expression of NKX2-5 gene.The P19 cells were cultured in suspension for 4 days,and the formed aggregates were transferred to Petri dish for adherent culture.On days 4,8,12,and 16 of the adherent culture,the expressions of ct-saicomeric actin(α-SA)and cardiac troponin T(cTnT)were detected with double-labeling immunofluorescence and Western blot.The ultrastruetural changes were observed on day 16.Results In the transfected group,no expression of α-SA and cTnT was found on day 4,and the expression of these 2 proteins or co-expression existed on days 8,12,and 16.There were early cell junction and myofilament-like structure in the cytoplasm of some cells in the transfected group.In the non-transfected group,these 2 proteins were negative,and no differentiated cell was found.Conclusion Stable expression of NKX2-5 gene can induce cardiomyocyte differentiation from P19 cells,but the P19 cells with stable expression of JVKX2-5 gene is not suitable to be an in vitro model of cardiac development.

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The Holt-Oram syndrome (HOS) is an autosomal dominant condition characterized by upper limb and cardiac malformations. Mutations in the TBX5 gene cause HOS and have also been associated with isolated heart and arm defects. Interactions between the TBX5, GATA4 and NKX2.5 proteins have been reported in humans. We screened the TBX5, GATA4, and NKX2.5 genes for mutations, by direct sequencing, in 32 unrelated patients presenting classical (8) or atypical HOS (1), isolated congenital heart defects (16) or isolated upper-limb malformations (7). Pathogenic mutations in the TBX5 gene were found in four HOS patients, including two new mutations (c.374delG; c.678G > T) in typical patients, and the hotspot mutation c.835C > T in two patients, one of them with an atypical HOS phenotype involving lower-limb malformations. Two new mutations in the GATA4 gene were found in association with isolated upper-limb malformations, but their clinical significance remains to be established. A previously described possibly pathogenic mutation in the NKX2.5 gene (c.73C > 7) was detected in a patient with isolated heart malformations and also in his clinically normal father.

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Objective:To investigate mRNA expression of cardiac related genes of NKX2.5,TBX5 and GATA4 in patients with tetralogy of fallot(TOF). Methods:A total of 10 TOF patients(TOF group)from 4 months to 8 years with the mean age of 3.5 years were recruited in our hospital from June to December 2005.The patients were diagnosed by typical clinical manifestation and cardiac color echocardiogram, the diagnosis was confirmed by cardiac surgery.6 non-congenital heart disease children were selected as Control group, and they were from 4 months to 9 years with the mean age of 3.8 years.The myocardial total RNA was extracted,the related cDNA was obtained by RT-PCR.The product cDNA was amplified with fluorescent quantitative PCR in order to compare the differences of NKX2.5,TBX5,GATA4 and GAPDH mRNA expression between TOF group and Control group. Results:NKX2.5 mRNA expression in TOF group was statistically decreased than that in Control group,while there were no statistical changes found in TBX5 and GATA4 mRNA expression between TOF group and Control group. Conclusion:The mRNA expression of NKX2.5,TBX5 and GATA4 were found in myocardium development.TOF was possibly related to decreased NKX2.5 mRNA expression.

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Objective To study the expression of NKx2.5 on the heart of offspring during the development of embryo,whose mother is deficient of folic acid.Methods 1.Control group involving 18 rats and study group involving 18 rats were chosen from the total 36 adult female SD rats randomly copulate with the male normal rats after feeding different fodder for 2 weeks.The heart of the 13.5 days,17.5 days embryos and the newborns were obtained;2.the expression of NKx2.5mRNA by RT-PCR was observed;3.the expression of NKx2.5 protein by Western-blotting was investigated.Results 1.The expression of NKx2.5 mRNA of study group was weaker than control group in heart of the 13.5 days,17.5 days embryos and the newborns(P