Gabor Szinnai

NKX2-1 Mutations Leading to Surfactant Protein Promoter Dysregulation Cause Interstitial Lung Disease in "Brain-Lung-Thyroid Syndrome''

NKX2‐1 (NK2 homeobox 1) is a critical regulator of transcription for the surfactant protein (SP)‐B and ‐C genes (SFTPB and SFTPC, respectively). We identified and functionally characterized two new de novo NKX2‐1 mutations c.493C>T (p.R165W) and c.786_787del2 (p.L263fs) in infants with closely similar severe interstitial lung disease (ILD), hypotonia, and congenital hypothyroidism. Functional analyses using A549 and HeLa cells revealed that NKX2‐1‐p.L263fs induced neither SFTPB nor SFTPC promoter activation and had a dominant negative effect on wild‐type (WT) NKX2‐1. In contrast,NKX2‐1‐p.R165W activated SFTPC, to a significantly greater extent than did WTNKX2‐1,whileSFTPB activation was only significantly reduced in HeLa cells. In accordance with our in vitro data, we found decreased amounts of SP‐B and SP‐C by western blot in bronchoalveolar lavage fluid (patient with p.L263fs) and features of altered surfactant protein metabolism on lung histology (patient with NKX2‐1‐p.R165W). In conclusion, ILD in patients with NKX2‐1 mutations was associated with altered surfactant protein metabolism, and both gain and loss of function of the mutated NKX2‐1 genes on surfactant protein promoters were associated with ILD in “Brain‐Lung‐Thyroid syndrome”.

High copeptin concentrations in umbilical cord blood after vaginal delivery and birth acidosis

CONTEXT The pituitary-secreted nonapeptide arginine-vasopressin (AVP) is unstable and therefore unsuited for diagnostic use, but its secretion can be estimated by measuring copeptin, the C-terminal portion of the AVP precursor (pro-AVP). OBJECTIVE Our objective was to investigate perinatal factors affecting copeptin concentrations in infants at birth and at 3 d of life. DESIGN AND SETTING We conducted a prospective cross-sectional study at a tertiary university hospital. PATIENTS Copeptin plasma concentrations were evaluated in 177 infants at birth, including 117 paired arterial/venous umbilical cord and 102 venous blood samples obtained at 3 d of life. MAIN OUTCOME MEASURE Copeptin concentrations were determined by a C-terminal pro-AVP luminescence immunoassay. RESULTS Arterial umbilical cord copeptin concentrations were consistently higher than matched venous ones (median 18 vs. 10 pmol/liter, P < 0.001), but both values were closely related (R(s) = 0.825; P < 0.001), and both were negatively related to arterial umbilical cord pH (R(s) arterial/venous = -0.578/-0.639; P < 0.001). Although exceedingly high copeptin concentrations were observed after vaginal birth in umbilical cord arterial [median (5-95% range) = 1610 (85-5000) pmol/liter] and venous [793 (6-4836) pmol/liter] plasma, copeptin concentrations were low after primary cesarean section [arterial/venous = 8 (3-907)/5 (5-504) pmol/liter]. Postnatal body weight loss was associated with increased copeptin concentrations at d 3 (R(s) = 0.438; P < 0.001) and was inversely related to copeptin concentrations at birth (R(s) = -0.289 and -0.309; both P = 0.001). CONCLUSION Vaginal birth is associated with a large release of copeptin that exceeds all values published so far, including those in critically ill adult patients with shock or brain injury. Thus, vaginal birth is arguably the most intense stressor in life.

Clinical Genetics of Congenital Hypothyroidism

Congenital hypothyroidism (CH) is a state of insufficient thyroid hormone supply to the organism, starting in utero. Two forms of permanent primary or thyroidal CH are known. Thyroid dysgenesis (TD) describes a spectrum of defects of thyroid organogenesis. Five monogenetic forms due to mutations in TSHR, PAX8, NKX2-1, FOXE1 and NKX2-5 have been identified so far. Thyroid dyshormonogenesis comprises defects at every step of thyroid hormone synthesis. Mutations in 7 genes are well described causing iodine transport defect (SLC5A5), iodine organification defect (TPO, DUOX2, DUOXA2, SLC26A4), thyroglobulin (TG) synthesis or transport defect or iodotyrosine deiodinase (IYD/DEHAL1) deficiency. The new consensus guidelines for CH recommend genetic counseling for each family with an affected child. Mode of inheritance, recurrence rate and possible associated malformations in the context of syndromic forms should be outlined. Molecular genetic studies should be preceded by a detailed phenotypic description of the patients thyroid disease and a detailed family history. This review summarizes clinical, biochemical and radiological phenotypes and molecular aspects of the known genetic forms of TD and thyroid dyshormonogenesis relevant for genetic counseling and molecular studies.

Procalcitonin guidance to reduce antibiotic treatment of lower respiratory tract infection in children and adolescents (ProPAED): a randomized controlled trial.

Background Antibiotics are overused in children and adolescents with lower respiratory tract infection (LRTI). Serum-procalcitonin (PCT) can be used to guide treatment when bacterial infection is suspected. Its role in pediatric LRTI is unclear. Methods Between 01/2009 and 02/2010 we randomized previously healthy patients 1 month to 18 years old presenting with LRTI to the emergency departments of two pediatric hospitals in Switzerland to receive antibiotics either according to a PCT guidance algorithm established for adult LRTI or standard care clinical guidelines. In intention-to-treat analyses, antibiotic prescribing rate, duration of antibiotic treatment, and number of days with impairment of daily activities within 14 days of randomization were compared between the two groups. Results In total 337 children, mean age 3.8 years (range 0.1–18), were included. Antibiotic prescribing rates were not significantly different in PCT guided patients compared to controls (OR 1.26; 95% CI 0.81, 1.95). Mean duration of antibiotic exposure was reduced from 6.3 to 4.5 days under PCT guidance (−1.8 days; 95% CI −3.1, −0.5; P = 0.039) for all LRTI and from 9.1 to 5.7 days for pneumonia (−3.4 days 95% CI −4.9, −1.7; P<0.001). There was no apparent difference in impairment of daily activities between PCT guided and control patients. Conclusion PCT guidance reduced antibiotic exposure by reducing the duration of antibiotic treatment, while not affecting the antibiotic prescribing rate. The latter may be explained by the low baseline prescribing rate in Switzerland for pediatric LRTI and the choice of an inappropriately low PCT cut-off level for this population. Trial Registration Controlled-Trials.com ISRCTN17057980 ISRCTN17057980

Hes1 Is Required for Appropriate Morphogenesis and Differentiation during Mouse Thyroid Gland Development

Notch signalling plays an important role in endocrine development, through its target gene Hes1. Hes1, a bHLH transcriptional repressor, influences progenitor cell proliferation and differentiation. Recently, Hes1 was shown to be expressed in the thyroid and regulate expression of the sodium iodide symporter (Nis). To investigate the role of Hes1 for thyroid development, we studied thyroid morphology and function in mice lacking Hes1. During normal mouse thyroid development, Hes1 was detected from E9.5 onwards in the median anlage, and at E11.5 in the ultimobranchial bodies. Hes1 −/− mouse embryos had a significantly lower number of Nkx2-1-positive progenitor cells (p<0.05) at E9.5 and at E11.5. Moreover, Hes1 −/− mouse embryos showed a significantly smaller total thyroid surface area (−40 to −60%) compared to wild type mice at all study time points (E9.5−E16.5). In both Hes1 −/− and wild type mouse embryos, most Nkx2-1-positive thyroid cells expressed the cell cycle inhibitor p57 at E9.5 in correlation with low proliferation index. In Hes1 −/− mouse embryos, fusion of the median anlage with the ultimobranchial bodies was delayed by 3 days (E16.5 vs. E13.5 in wild type mice). After fusion of thyroid anlages, hypoplastic Hes1 −/− thyroids revealed a significantly decreased labelling area for T4 (−78%) and calcitonin (−65%) normalized to Nkx2-1 positive cells. Decreased T4-synthesis might be due to reduced Nis labelling area (−69%). These findings suggest a dual role of Hes1 during thyroid development: first, control of the number of both thyrocyte and C-cell progenitors, via a p57-independent mechanism; second, adequate differentiation and endocrine function of thyrocytes and C-cells.

Plasma Copeptin in Preterm Infants - a Highly Sensitive Marker of Fetal and Neonatal Stress

CONTEXT Copeptin is a stable by-product of arginine-vasopressin synthesis and reflects its secretion by the pituitary. OBJECTIVE The objective of the study was to investigate perinatal factors affecting copeptin concentrations in preterm infants at birth and at 3 d of life. DESIGN AND SETTING This was a prospective cross-sectional study at two Swiss university hospitals. PATIENTS One hundred sixty-seven preterm infants were enrolled, 59 infants born between 24 and 31 wk gestational age, 50 infants between 32 and 34 wk, and 58 between 35 and 36 wk. MAIN OUTCOME MEASURE Plasma copeptin concentrations, determined by a CT-proAVP-luminescence-immunoassay, were measured. RESULTS Copeptin at birth was significantly higher in preterm infants born vaginally [median (range) 366 (1-2900) pmol/liter, n = 43] than those born by cesarean section [6.9 (2-1580), n = 124]. In infants born after cesarean without prior labor (n = 66), estimated fetal weight less than the fifth percentile, suspect fetal heart rate, compromised placental perfusion, and chorioamnionitis were each associated with significantly elevated cord copeptin. Copeptin at 3 d of life was not associated with cord blood copeptin but inversely related to gestational age (Rs = -0.6, P < 0.001) and birth weight (Rs -0.612, P < 0.001). Day 3 copeptin increased alongside the level of mechanical respiratory support. CONCLUSION Copeptin is a highly sensitive marker of perinatal stress.

Genetics of normal and abnormal thyroid development in humans

The most frequent cause of congenital hypothyroidism is thyroid dysgenesis. Thyroid dysgenesis summarizes a spectrum of developmental abnormalities of the embryonic thyroid ranging from complete absence of the thyroid gland (athyreosis), to a normally located but too small thyroid (hypoplasia), or an abnormally located thyroid gland (ectopy). Although considered a sporadic disease, distinct genetic forms of isolated or syndromic thyroid dysgenesis have been described in recent years. However, genetics of thyroid dysgenesis (TD) are mostly not following simple Mendelian patterns, and beside monogenic, multigenic and epigenetic mechanisms need to be considered. The review will highlight the molecular mechanisms of thyroid organogenesis, clinical and genetic features of the different monogenetic forms of thyroid dysgenesis, the aspects relevant for diagnosis and counseling of affected families and current research strategies to get more insight into the non-Medelian mechanisms of normal and abnormal thyroid development.

Extreme phenotypic variability of thyroid dysgenesis in six new cases of congenital hypothyroidism due to PAX8 gene loss-of-function mutations

CONTEXT Within the last two decades, heterozygous loss-of-function PAX8 mutations have been reported in patients with a wide degree of thyroid gland dysfunction and growth despite the presence of identical mutations. OBJECTIVES To search for PAX8 mutations in a cohort of patients with congenital hypothyroidism (CH) and various types of thyroid gland defects. DESIGN A cross-sectional study was conducted in a cohort of patients. SETTING The French neonatal screening program was used for recruiting patients. PATIENTS A total of 118 patients with CH, including 45 with familial and 73 with sporadic diseases, were included in this study. The thyroid gland was normal in 23 patients had hypoplasia, 25 had hemithyroid agenesis, 21 had athyreosis, and 21 had ectopy. RESULTS We found four different PAX8 mutations (p.R31C, p.R31H, p.R108X, and p.I47T) in ten patients (six patients with CH and four family members), two with sporadic and eight with familial diseases. Imaging studies performed in the index cases showed ectopic thyroid gland (n=2), hypoplasia (n=2), eutopic lobar asymmetry (n=1), and eutopic gland compatible with dyshormonogenesis (n=1). The previously reported p.R31C and the novel p.I47T PAX8 mutations are devoid of activity. CONCLUSION Four different PAX8 mutations were detected in six index patients with CH (ten total subjects). The p.R31C, p.R31H, and p.R108X mutations have been reported. The novel p.I47T PAX8 mutation presented loss of function leading to CH. Thyroid ectopy was observed in two cases of PAX8 (p.R31H) mutation, a finding that has not been reported previously. We observed a high inter-individual and intra-familial variability of the phenotype in PAX8 mutations, underlining that population genetic studies for CH should include patients with various clinical presentations.

Multiplex Ligation-Dependent Probe Amplification Improves the Detection Rate of NKX2.1 Mutations in Patients Affected by Brain-Lung-Thyroid Syndrome

Background: NKX2.1 mutations have been identified in patients displaying complete or partial brain-lung-thyroid syndrome, which can include benign hereditary chorea (BHC), hypothyroidism and/or lung disease. Aims and Methods: We evaluated the recently developed Multiplex Ligation-dependent Probe Amplification (MLPA) method to assess the relative copy number of genes. The goal was to determine if MLPA could improve, in addition to direct sequencing, the detection rate of NKX2.1 mutations in a phenotype-selected cohort of 24 patients affected by neurological, thyroid and/or pulmonary disorders. Results: Direct sequencing revealed two heterozygous mutations. Using MLPA, we identified two further heterozygous NKX2.1 gene deletions. MLPA increased the detection rate by 50%. All patients with gene deletions identified were affected by BHC and congenital hypothyroidism. Conclusion: MLPA should be considered as a complementary tool in patients with partial or total brain-lung-thyroid syndrome when direct sequencing failed to identify NKX2.1 mutations. All patients with an NKX2.1 mutation had BHC and congenital hypothyroidism, emphasizing the high prevalence of these signs associated with defective NKX2.1 alleles.

Discordant Gene Expression Signatures and Related Phenotypic Differences in Lamin A- and A/C-Related Hutchinson-Gilford Progeria Syndrome (HGPS)

Hutchinson-Gilford progeria syndrome (HGPS) is a genetic disorder displaying features reminiscent of premature senescence caused by germline mutations in the LMNA gene encoding lamin A and C, essential components of the nuclear lamina. By studying a family with homozygous LMNA mutation (K542N), we showed that HGPS can also be caused by mutations affecting both isoforms, lamin A and C. Here, we aimed to elucidate the molecular mechanisms underlying the pathogenesis in both, lamin A- (sporadic) and lamin A and C-related (hereditary) HGPS. For this, we performed detailed molecular studies on primary fibroblasts of hetero- and homozygous LMNA K542N mutation carriers, accompanied with clinical examinations related to the molecular findings. By assessing global gene expression we found substantial overlap in altered transcription profiles (13.7%; 90/657) in sporadic and hereditary HGPS, with 83.3% (75/90) concordant and 16.7% (15/90) discordant transcriptional changes. Among the concordant ones we observed down-regulation of TWIST2, whose inactivation in mice and humans leads to loss of subcutaneous fat and dermal appendages, and loss of expression in dermal fibroblasts and periadnexial cells from a LMNA K542N/K542N patient further confirming its pivotal role in skin development. Among the discordant transcriptional profiles we identified two key mediators of vascular calcification and bone metabolism, ENPP1 and OPG, which offer a molecular explanation for the major phenotypic differences in vascular and bone disease in sporadic and hereditary HGPS. Finally, this study correlates reduced TWIST2 and OPG expression with increased osteocalcin levels, thereby linking altered bone remodeling to energy homeostasis in hereditary HGPS.