Heterozygous Mutations of the DUOXA2 and DUOX2 Genes in Dizygotic Twins with Congenital Hypothyroidism.

BACKGROUND: The mutations in the dual oxidase maturation factor 2 (DUOXA2) and dual oxidase 2 (DUOX2) genes have been identified in patients with congenital hypothyroidism (CH). This study reports a set of dizygotic twins with CH due to the mutations in the DUOX2/DUOXA2 system. METHODS: The dizygotic twins, a boy and a girl, both aged 7 years, were born to euthyroid nonconsanguineous parents; they were diagnosed with CH at neonatal screening and were enrolled in this study. The DUOXA2, DUOX2, paired box 8 (PAX8), thyroid peroxidase (TPO), and thyrotropin receptor (TSHR) genes were considered for mutation screening. Genomic DNA was extracted from peripheral blood leukocytes, and Sanger sequencing was used to screen for the mutations in the exon fragments. Family members of the patients were also enrolled and evaluated. RESULTS: The fraternal twins each harbored a single heterozygous mutation, including c.738C>G (p.Y246X) in the boy inherited from the paternal DUOXA2 allele and c.2654G>A (p.R885Q) in the girl from the maternal DUOX2 allele. The two mutations have been previously reported. The boy showed enlarged thyroid lobes and a little calcification in the left lobe, while the girl's thyroid gland was severely underdeveloped and the girl had obvious complications due to irregular treatment. The germline mutations from this family were consistent with an autosomal recessive inheritance pattern. No mutations in the PAX8, TPO, and TSHR genes were detected in this study. CONCLUSIONS: The inactivating mutations in the DUOXA2 (p.Y246X) and DUOX2 (p.R885Q) genes were identified in a set of dizygotic twins with CH. The girl was more severe in several aspects than her brother. The similar genetic defect resulted in very different outcomes.

Two novel TSHR gene mutations (p.R528C and c.392+4del4) associated with congenital hypothyroidism.

Inactivating mutations of the thyrotropin receptor (TSHR) gene are responsible for non-goitrogenic congenital hypothyroidism (CHNG). This study aimed to investigate mutations in the TSHR gene in 20 children with CHNG. Genomic DNA was extracted from peripheral blood leukocytes and was used for mutation screening by direct sequencing. Analyses of the TSHR gene revealed two novel variants in a 2-year-old boy with thyroid hypoplasia: a missense mutation c.1582C>T (p.R528C) and a splice-site deletion c.392+4del4. Bioinformatics analysis demonstrated that both variants are capable of causing disease. Family members of the patient with two mutations and normal controls were also recruited and investigated. Germline mutations from the proband's family were consistent with an autosomal recessive inheritance pattern. These findings indicate that two novel inactivating mutations (p.R528C and c.392+4del4) in the TSHR gene can cause CHNG.

Mutational spectrum of phenylketonuria in Jiangsu province.

UNLABELLED: Phenylketonuria (PKU) is caused by variants in the phenylalanine hydroxylase (PAH) gene. We systematically investigated all 13 exons of the PAH gene and their flanking introns in 31 unrelated patients and their parents using next-generation sequencing (NGS). A total of 33 different variants were identified in 58 of 62 mutant PAH alleles. The prevalent variants with a relative frequency of 5 % or more were c.721C > T, c.1068C > A, c.611A > G, c.1197A > T, c.728G > A, c.331C > T, and c.442-1G > A. One novel variant was identified in this study-c.699C > G. We studied genotype-phenotype correlations using the Guldberg arbitrary value (AV) system, which revealed a consistency rate of 38 % (8/21) among the 21 predicted phenotypes. The genotype-based prediction of BH4 responsiveness was also evaluated, and 14 patients (45.2 %) were predicted to be BH4 responsive. CONCLUSION: This study presents the spectrum of PAH variants in Jiangsu province. The information obtained from the genotype-based prediction of BH4 responsiveness might be used for the rational selection of candidates for BH4 testing. WHAT IS KNOWN: • Phenylketonuria (PKU) is caused by variants in the phenylalanine hydroxylase (PAH) gene. • The spectrum of PAH variants in different Chinese populations has been reported. What is new: • This is the first report on the spectrum of PAH variants in Jiangsu province. • This study identified one novel PAH variant-c.699C>G-and and tries to show a genotype-phenotype relationship also regarding BH4-responsiveness.

Novel genetic variants in the TPO gene cause congenital hypothyroidism.

BACKGROUND: Mutations in the dual oxidase maturation factor 2 (DUOXA2) and thyroid peroxidase (TPO) genes have been reported to cause goitrous congenital hypothyroidism (GCH). The aim of this study was to determine the genetic basis of GCH in affected children. METHODS: Thirty children with GCH were enrolled for molecular analysis of the DUOXA2 and TPO genes. All subjects underwent clinical examination and laboratory testing. Genomic DNA was extracted from peripheral blood leukocytes, and Sanger sequencing was used to screen for DUOXA2 and TPO gene mutations in the exon fragments amplified from the extracted DNA. Family members of those patients with mutations were also enrolled and evaluated. RESULTS: Analysis of the TPO gene revealed six genetic variants, including two novel heterozygous mutations, c.1970T> C (p.I657T) and c.2665G> T (p.G889X), and four mutations that have been reported previously (c.670_672del, c.2268dup, c.2266T> C and c.2647C> T). Three patients harbored the same mutation c.2268dup. The germline mutations from four unrelated families were consistent with an autosomal recessive inheritance pattern. Conversely, no mutations in the DUOXA2 gene were detected. CONCLUSION: Two novel inactivating mutations (c.1970T> C and c.2665G> T) in the TPO gene were identified. The c.2268dup mutation occurred frequently. No mutations in the DUOXA2 gene were detected in this study.

Compound Heterozygous Mutations in the DUOX2/DUOXA2 Genes Cause Congenital Hypothyroidism.

The mutations in the dual oxidase 2 (DUOX2) and dual oxidase maturation factor 2 (DUOXA2) genes can cause congenital hypothyroidism (CH). This study reports the pedigree with goitrous congenital hypothyroidism (GCH) due to the coexistence of heterozygous mutations in the DUOX2 and DUOXA2 genes. The two sisters with GCH were diagnosed with CH at neonatal screening and were enrolled in this study. The DUOX2, DUOXA2, and thyroid peroxidase (TPO) genes were considered for genetic defects screening. Family members of the patients and normal controls were also enrolled and evaluated. The two girls harbored compound heterozygous mutations, including a new mutation of c.2654G>T (p.R885L) in the maternal DUOX2 allele and c.738C>G (p.Y246X) in the paternal DUOXA2 allele, that has been previously reported. The germline mutations from the families were consistent with an autosomal recessive inheritance pattern. No mutations in the TPO gene and the controls were observed.

Coexistence of resistance to thyroid hormone and ectopic thyroid: ten-year follow-up.

Resistance to thyroid hormone (RTH) coexisting with ectopic thyroid is rare. Here we report a case of RTH with ectopic thyroid. A ten-year-old girl had been misdiagnosed as congenital hypothyroidism and treated with levothyroxine since she was born. Ten-year follow-up showed that the elevated thyrotropin was never suppressed by levothyroxine and no signs indicating hyperthyroidism or hypothyroidism despite elevated FT3 and FT4 levels. Therefore the girl developed no defects in physical and cognitive development. Pituitary adenoma was excluded by magnetic resonance imaging. Ultrasonography did not find the thyroid gland in the normal place, while the thyroid scan found a large lingual thyroid gland. The octreotide inhibition test showed a reduction in thyrotropin by 41.98%. No mutation was detected in the thyroid hormone receptor (THR) ß, THRα, thyrotropin receptor (TSHR), and GNAS1 genes. To our knowledge, it is an interesting RTH case coexisting with lingual thyroid.

Compound heterozygous mutations (p.T561M and c.2422delT) in the TPO gene associated with congenital hypothyroidism.

BACKGROUND: The objective of the study was to determine the genetic basis of goitrous congenital hypothyroidism (GCH) in Chinese siblings. METHODS: The proband and her younger brother with GCH were enrolled for molecular analysis of the dual oxidase 2 (DUOX2), dual oxidase maturation factor 2 (DUOXA2), and thyroid peroxidase (TPO) genes. Mutation screening was performed by Sanger sequencing the fragments amplified from genomic DNA. The detected mutations were verified among the close relatives of the patients and 105 controls. All participants underwent clinical examination and laboratory tests. RESULTS: Analysis of the TPO gene revealed two heterozygous mutations, the frameshift mutation c.2422delT in the exon14 of the TPO gene, that has been reported previously, and a novel missense mutation c.1682C>T (p.T561M) in the exon10 of the TPO gene. Nine family members of the patients were enrolled for mutation screening. The patients' parents and grandfathers harbored a single heterozygous mutation. The germline mutations from this family were consistent with an autosomal recessive inheritance pattern. No mutations in the DUOXA2 and DUOX2 genes were observed. CONCLUSIONS: The inactivating mutations (c.2422delT and p.T561M) in the TPO gene were identified in the Chinese siblings with GCH. The compound heterozygous mutations can cause GCH.

A Novel c.554+5C>T Mutation in the DUOXA2 Gene Combined with p.R885Q Mutation in the DUOX2 Gene Causing Congenital Hypothyroidism.

The coexistence of mutations in the dual oxidase maturation factor 2 (DUOXA2) and dual oxidase 2 (DUOX2) genes is rarely identified in congenital hypothyroidism (CH). This study reports a boy with CH due to a novel splice-site mutation in the DUOXA2 gene and a missense mutation in the DUOX2 gene. A four-year-old boy was diagnosed with CH at neonatal screening and was enrolled in this study. The DUOXA2, DUOX2, thyroid peroxidase (TPO), and thyrotropin receptor (TSHR) genes were considered for genetic defects screening. Genomic DNA was extracted from peripheral blood leukocytes, and Sanger sequencing was used to screen the mutations in the exon fragments. Family members of the patient and the controls were also enrolled and evaluated. The boy harbored compound heterozygous mutations including a novel splice-site mutation c.554+5C>T in the maternal DUOXA2 allele and c.2654G>A (p.R885Q) in the paternal DUOX2 allele. The germline mutations from his parents were consistent with an autosomal recessive inheritance pattern. No mutations in the TPO and TSHR genes were detected. A novel splice-site mutation c.554+5C>T in the DUOXA2 gene and a mutation p.R885Q in the DUOX2 gene were identified in a 4-year-old patient with goitrous CH.

Evaluation of inflammatory and oxidative biomarkers in children with well-controlled congenital hypothyroidism.

OBJECTIVE: To investigate well-controlled congenital hypothyroidism on the markers associated with early kidney injury and oxidative DNA damage. METHODS: Twenty-three children with euthyroid congenital hypothyroidism aged 3-6 years and 19 age- and gender-matched controls were enrolled. Serum levels of albumin, C-reactive protein, cysteine C, globulin, pre-albumin, and total protein were detected. Urine levels of albumin, fibrin degradation products, IgG, ß2-microglobulin, and 8-hydroxydeoxyguanosine (8-OHdG) were also measured. Clinical and biochemical characteristics were evaluated between the two groups. RESULTS: Serum levels of C-reactive protein were higher, but pre-albumin was lower in patients with congenital hyperthyroidism compared with the controls (all p<0.001). Urinary levels of IgG were higher in patients with congenital hyperthyroidism than in the controls (p=0.011). However, urinary levels of albumin excretion and 8-OHdG were similar to those in the controls. Serum pre-albumin levels were negatively correlated with urinary 8-OHdG levels (r=-0.479, p=0.016) in patients with congenital hypothyroidism. CONCLUSION: It is concluded that inflammatory and oxidative markers were slightly altered in well-controlled congenital hypothyroidism. The levels of urinary 8-OHdG and albumin excretion were not significantly different.

Ovalbumin enhances YKL-40, IL-5, GM-CSF, and eotaxin expression simultaneously in primarily cultured mouse tracheal epithelial cells.

Epithelial inflammation and eosinophil infiltration are crucial for the pathogenesis of asthma. Many inflammatory mediators, such as YKL-40, interleukin -5 (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF), and eotaxin, are important for the development of allergic airway inflammation. This study is aimed at investigating the impact of treatment with ovalbumin (OVA) on the levels of those inflammatory mediators in primarily cultured mouse tracheal epithelial cells. Mouse tracheal epithelial cells were isolated and identified by immunofluorescent staining; the isolated mouse tracheal epithelial cells expressed cytokeratins. Treatment with OVA for 24 or 48 h significantly increased the relative levels of YKL-40, IL-5, GM-CSF, and eotaxin mRNA transcripts and YKL-40, IL-5, GM-CSF, and eotaxin proteins secreted in the supernatants of cultured cells, as compared with that in the untreated control cells (P < 0.01, P < 0.05, respectively). The levels of YKL-40 expression were correlated positively with the levels of IL-5, GM-CSF, and eotaxin expression in the OVA-treated cells. These data indicated that treatment with OVA simultaneously enhanced YKL-40, IL-5, GM-CSF, and eotaxin expression in the cultured mouse tracheal epithelial cells in vitro. These inflammatory mediators may synergistically contribute to the pathogenesis of allergic inflammation, and this study may help to understand the role of YKL-40 in the pathogenesis of asthma.

Coexistence of resistance to thyroid hormone and ectopic thyroid: ten-year follow-up

SUMMARY Resistance to thyroid hormone (RTH) coexisting with ectopic thyroid is rare. Here we report a case of RTH with ectopic thyroid. A ten-year-old girl had been misdiagnosed as congenital hypothyroidism and treated with levothyroxine since she was born. Ten-year follow-up showed that the elevated thyrotropin was never suppressed by levothyroxine and no signs indicating hyperthyroidism or hypothyroidism despite elevated FT3 and FT4 levels. Therefore the girl developed no defects in physical and cognitive development. Pituitary adenoma was excluded by magnetic resonance imaging. Ultrasonography did not find the thyroid gland in the normal place, while the thyroid scan found a large lingual thyroid gland. The octreotide inhibition test showed a reduction in thyrotropin by 41.98%. No mutation was detected in the thyroid hormone receptor (THR) β, THRα, thyrotropin receptor (TSHR), and GNAS1 genes. To our knowledge, it is an interesting RTH case coexisting with lingual thyroid.