Knockout mice with pituitary malformations help identify human cases of hypopituitarism.

BACKGROUND: Congenital hypopituitarism (CH) and its associated syndromes, septo-optic dysplasia (SOD) and holoprosencephaly (HPE), are midline defects that cause significant morbidity for affected people. Variants in 67 genes are associated with CH, but a vast majority of CH cases lack a genetic diagnosis. Whole exome and whole genome sequencing of CH patients identifies sequence variants in genes known to cause CH, and in new candidate genes, but many of these are variants of uncertain significance (VUS). METHODS: The International Mouse Phenotyping Consortium (IMPC) is an effort to establish gene function by knocking-out all genes in the mouse genome and generating corresponding phenotype data. We used mouse embryonic imaging data generated by the Deciphering Mechanisms of Developmental Disorders (DMDD) project to screen 209 embryonic lethal and sub-viable knockout mouse lines for pituitary malformations. RESULTS: Of the 209 knockout mouse lines, we identified 51 that have embryonic pituitary malformations. These genes not only represent new candidates for CH, but also reveal new molecular pathways not previously associated with pituitary organogenesis. We used this list of candidate genes to mine whole exome sequencing data of a cohort of patients with CH, and we identified variants in two unrelated cases for two genes, MORC2 and SETD5, with CH and other syndromic features. CONCLUSIONS: The screening and analysis of IMPC phenotyping data provide proof-of-principle that recessive lethal mouse mutants generated by the knockout mouse project are an excellent source of candidate genes for congenital hypopituitarism in children.

Exome Sequencing has a high diagnostic rate in sporadic congenital hypopituitarism and reveals novel candidate genes.

CONTEXT: The pituitary gland is key for childhood growth, puberty, and metabolism. Pituitary dysfunction is associated with a spectrum of phenotypes, from mild to severe. Congenital Hypopituitarism (CH) is the most commonly reported pediatric endocrine dysfunction with an incidence of 1:4000, yet low rates of genetic diagnosis have been reported. OBJECTIVE: We aimed to unveil the genetic etiology of CH in a large cohort of patients from Argentina. METHODS: We performed whole exome sequencing of 137 unrelated cases of CH, the largest cohort examined with this method to date. RESULTS: Of the 137 cases, 19.1% and 16% carried pathogenic or likely pathogenic variants in known and new genes, respectively, while 28.2% carried variants of uncertain significance. This high yield was achieved through the integration of broad gene panels (genes described in animal models and/or other disorders), an unbiased candidate gene screen with a new bioinformatics pipeline (including genes high loss of function intolerance), and analysis of copy number variants. Three novel findings emerged. First, the most prevalent affected gene encodes the cell adhesion factor ROBO1. Affected children had a spectrum of phenotypes, consistent with a role beyond pituitary stalk interruption syndrome. Second, we found that CHD7 mutations also produce a phenotypic spectrum, not always associated with full CHARGE syndrome. Third, we add new evidence of pathogenicity in the genes PIBF1 and TBC1D32, and report 13 novel candidate genes associated with CH (e.g. PTPN6, ARID5B). CONCLUSION: Overall, these results provide an unprecedented insight into the diverse genetic etiology of hypopituitarism.

The p.Cys1281Tyr variant in the hinge module/flap region of thyroglobulin causes intracellular transport disorder and congenital hypothyroidism.

Congenital hypothyroidism (CH) due to thyroglobulin (TG) variants causes very low serum TG levels with normal or enlarged thyroid glands, depending on the severity of the defect, and with autosomal recessive inheritance. The purpose of this study was to functionally characterize p.Cys1281Tyr variant in the TG gene in order to increase our knowledge of the molecular mechanisms associated with CH. In order to find evidence that support the hypothesis that the p.Cys1281Tyr variant would affect the TG folding were performed amino acid prediction, 3D modeling and transient expression analysis in HEK293T cells. 18 of the 21″in silico" algorithms predict a deleterious effect of the p.Cys1281Tyr variant. The full-length 3D model p.Cys1281Tyr TG showed disulfide bond cleavage between the cysteines at positions 1249 and 1281 and rearrangement of the TG structure, while transient expression analysis indicated that p.Cys1281Tyr causes retention of the protein inside the cell. Consequently, these results show that this pathogenic variant makes it impossible for TG to fulfill its function in the biosynthesis process of thyroid hormones, causing CH. In conclusion, our results confirm the pathophysiological importance of misfolding of TG as a consequence of p.Cys1281Tyr variant located in the hinge module/flap region of TG.

Mutational screening of the TPO and DUOX2 genes in Argentinian children with congenital hypothyroidism due to thyroid dyshormonogenesis.

PURPOSE: Primary congenital hypothyroidism (CH) is the most common endocrine disease in children and one of the preventable causes of both cognitive and motor deficits. We present a genetic and bioinformatics investigation of rational clinical design in 17 Argentine patients suspected of CH due to thyroid dyshormonogenesis (TDH). METHODS: Next-Generation Sequencing approach was used to identify variants in Thyroid Peroxidase (TPO) and Dual Oxidase 2 (DUOX2) genes. A custom panel targeting 7 genes associated with TDH [(TPO), Iodothyrosine Deiodinase I (IYD), Solute Carrier Family 26 Member 4 (SLC26A4), Thyroglobulin (TG), DUOX2, Dual Oxidase Maturation Factor 2 (DUOXA2), Solute Carrier Family 5 Member 5 (SLC5A5)] and 4 associated with thyroid dysembryogenesis [PAX8, FOXE1, NKX2-1, Thyroid Stimulating Hormone Receptor (TSHR)] has been designed. Additionally, bioinformatic analysis and structural modeling were carried out to predict the disease-causing potential variants. RESULTS: Four novel variants have been identified, two in TPO: c.2749-2 A > C and c.2752_2753delAG, [p.Ser918Cysfs*62] and two variants in DUOX2 gene: c.425 C > G [p.Pro142Arg] and c.2695delC [p.Gln899Serfs*21]. Eighteen identified TPO, DUOX2 and IYD variants were previously described. We identified potentially pahogenic biallelic variants in TPO and DUOX2 in 7 and 2 patients, respectively. We also detected a potentially pathogenic monoallelic variant in TPO and DUOX2 in 7 and 1 patients respectively. CONCLUSIONS: 22 variants have been identified associated with TDH. All described novel mutations occur in domains important for protein structure and function, predicting the TDH phenotype.

Silent but Not Harmless: A Synonymous SLC5A5 Gene Variant Leading to Dyshormonogenic Congenital Hypothyroidism.

Background: Congenital iodide transport defect (ITD) is an uncommon cause of dyshormonogenic congenital hypothyroidism characterized by the absence of active iodide accumulation in the thyroid gland. ITD is an autosomal recessive disorder caused by loss-of-function variants in the sodium/iodide symporter (NIS)-coding SLC5A5 gene. Objective: We aimed to identify, and if so to functionally characterize, novel ITD-causing SLC5A5 gene variants in a cohort of five unrelated pediatric patients diagnosed with dyshormonogenic congenital hypothyroidism with minimal to absent 99mTc-pertechnetate accumulation in the thyroid gland. Methods: The coding region of the SLC5A5 gene was sequenced using Sanger sequencing. In silico analysis and functional in vitro characterization of a novel synonymous variant were performed. Results: Sanger sequencing revealed a novel homozygous synonymous SLC5A5 gene variant (c.1326A>C in exon 11). In silico analysis revealed that the c.1326A>C variant is potentially deleterious for NIS pre-mRNA splicing. The c.1326A>C variant was predicted to lie within a putative exonic splicing enhancer reducing the binding of splicing regulatory trans-acting protein SRSF5. Splicing minigene reporter assay revealed that c.1326A>C causes exon 11 or exon 11 and 12 skipping during NIS pre-mRNA splicing leading to the NIS pathogenic variants p.G415_P443del and p.G415Lfs*32, respectively. Significantly, the frameshift variant p.G415Lfs*32 is predicted to be subjected to degradation by nonsense-mediated decay. Conclusions: We identified the first exonic synonymous SLC5A5 gene variant causing aberrant NIS pre-mRNA splicing, thus expanding the mutational landscape of the SLC5A5 gene leading to dyshormonogenic congenital hypothyroidism.

A Novel SLC5A5 Variant Reveals the Crucial Role of Kinesin Light Chain 2 in Thyroid Hormonogenesis.

CONTEXT: Iodide transport defect (ITD) (Online Mendelian Inheritance in Man No. 274400) is an uncommon cause of dyshormonogenic congenital hypothyroidism due to loss-of-function variants in the SLC5A5 gene, which encodes the sodium/iodide symporter (NIS), causing deficient iodide accumulation in thyroid follicular cells. OBJECTIVE: This work aims to determine the molecular basis of a patient's ITD clinical phenotype. METHODS: The propositus was diagnosed with dyshormonogenic congenital hypothyroidism with minimal 99mTc-pertechnetate accumulation in a eutopic thyroid gland. The propositus SLC5A5 gene was sequenced. Functional in vitro characterization of the novel NIS variant was performed. RESULTS: Sanger sequencing revealed a novel homozygous missense p.G561E NIS variant. Mechanistically, the G561E substitution reduces iodide uptake, because targeting of G561E NIS to the plasma membrane is reduced. Biochemical analyses revealed that G561E impairs the recognition of an adjacent tryptophan-acidic motif by the kinesin-1 subunit kinesin light chain 2 (KLC2), interfering with NIS maturation beyond the endoplasmic reticulum, and reducing iodide accumulation. Structural bioinformatic analysis suggests that G561E shifts the equilibrium of the unstructured tryptophan-acidic motif toward a more structured conformation unrecognizable to KLC2. Consistently, knockdown of Klc2 causes defective NIS maturation and consequently decreases iodide accumulation in rat thyroid cells. Morpholino knockdown of klc2 reduces thyroid hormone synthesis in zebrafish larvae leading to a hypothyroid state as revealed by expression profiling of key genes related to the hypothalamic-pituitary-thyroid axis. CONCLUSION: We report a novel NIS pathogenic variant associated with dyshormonogenic congenital hypothyroidism. Detailed molecular characterization of G561E NIS uncovered the significance of KLC2 in thyroid physiology.

Neonatal and Infant Reference Intervals for FSH, LH, Testosterone, Estradiol, Cortisol and DHEA-S by Electrochemiluminescence in Argentina.

BACKGROUND: Gonadotropin and steroid concentrations obtained in various laboratories cannot often be compared because of methodological differences. AIMS: to determine reference intervals for FSH, LH, T, E2, F and DHEA-S according to age and sex during the first year of life. METHODS: 1236 healthy infants (1-365 days of age) were recruited at Hospital de Niños in Córdoba, Argentina. Serum samples were analyzed using electrochemiluminescence, Cobas e601 analyzer. Reference Intervals and their confidence limits were estimated. RESULTS: Female FSH levels were higher than in males. LH and T levels were higher in males. E2 levels showed a difference between sexes after 60 days of age. F levels showed a wide variation, without differences between sexes. DHEA-S levels were higher at birth and decreased during the first year. CONCLUSION: These reference intervals may help to increase the diagnostic power for the assessment of endocrine disorders during the first year of life.

Genetic diagnosis of congenital hypopituitarism by a target gene panel: novel pathogenic variants in GLI2, OTX2 and GHRHR.

AIM: Congenital hypopituitarism has an incidence of 1:3500-10,000 births and is defined by the impaired production of pituitary hormones. Early diagnosis has an impact on management and genetic counselling. The clinical and genetic heterogeneity of hypopituitarism poses difficulties to select the order of genes to analyse. The objective of our study is to screen hypopituitarism genes (candidate and previously related genes) simultaneously using a target gene panel in patients with congenital hypopituitarism. METHODS: Screening of 117 subjects with congenital hypopituitarism for pathogenic variants in 26 genes associated with congenital hypopituitarism by massively parallel sequencing using a customized target gene panel. RESULTS: We found three novel pathogenic variants in OTX2 c.295C>T:p.Gln99*, GLI2 c.1681G>T:p.Glu561* and GHRHR c.820_821insC:p.Asp274Alafs*113, and the previously reported variants in GHRHR c.57+1G>A and PROP1 [c.301_302delAG];[c.109+1G>A]. CONCLUSIONS: Our results indicate that a custom-designed panel is an efficient method to screen simultaneously variants of biological and clinical relevance for congenital GH deficiency. A genetic diagnosis was possible in 5 out of 117 (4%) patients of our cohort. We identified three novel pathogenic variants in GHRHR, OTX2 and GLI2 expanding the spectrum of variants associated with congenital hypopituitarism.

Molecular analysis of thyroglobulin mutations found in patients with goiter and hypothyroidism.

Thyroid dyshormonogenesis due to thyroglobulin (TG) gene mutations have an estimated incidence of approximately 1 in 100,000 newborns. The clinical spectrum ranges from euthyroid to mild or severe hypothyroidism. Up to now, one hundred seventeen deleterious mutations in the TG gene have been identified and characterized. The purpose of the present study was to identify and characterize new mutations in the TG gene. We report eight patients from seven unrelated families with goiter, hypothyroidism and low levels of serum TG. All patients underwent clinical, biochemical and image evaluation. Sequencing of DNA, genotyping, as well as bioinformatics analysis were performed. Molecular analyses revealed three novel inactivating TG mutations: c.5560G>T [p.E1835*], c.7084G>C [p.A2343P] and c.7093T>C [p.W2346R], and four previously reported mutations: c.378C>A [p.Y107*], c.886C>T [p.R277*], c.1351C>T [p.R432*] and c.7007G>A [p.R2317Q]. Two patients carried homozygous mutations (p.R277*/p.R277*, p.W2346R/p.W2346R), four were compound heterozygous mutations (p.Y107*/p.R277* (two unrelated patients), p.R432*/p.A2343P, p.Y107*/p.R2317Q) and two siblings from another family had a single p.E1835* mutated allele. Additionally, we include the analysis of 48 patients from 31 unrelated families with TG mutations identified in our present and previous studies. Our observation shows that mutations in both TG alleles were found in 27 families (9 as homozygote and 18 as heterozygote compound), whereas in the remaining four families only one mutated allele was detected. The majority of the detected mutations occur in exons 4, 7, 38 and 40. 28 different mutations were identified, 33 of the 96 TG alleles encoded the change p.R277*. In conclusion, our results confirm the genetic heterogeneity of TG defects and the pathophysiological importance of the predicted TG misfolding and therefore thyroid hormone formation as a consequence of truncated TG proteins and/or missense mutations located within its ACHE-like domain.

Síndrome de interrupción del tallo pituitario: Relaciones clínicas, bioquímicas y neurorradiológicas / Pituitary stalk interruption syndrome: Clinical, biochemical and neuroradiological relationships

El síndrome de interrupción del tallo pituitario (PSIS) se caracteriza por la demostración neurorradiológica de un tallo pituitario ausente, interrumpido o hipoplásico, adenohipófisis aplásica/hipoplásica o neurohipófisis ectópica. Este síndrome se ha relacionado con formas severas de hipopituitarismo congénito (HPC), asociado a múltiples deficiencias de hormonas pituitarias (MPHD). Evaluamos a pacientes con HPC y PSIS, analizando los signos y los síntomas neonatales al diagnóstico, relacionándolos con las deficiencias hormonales pituitarias y signos neurorradiológicos presentes. Estudiamos retrospectivamente a 80 pacientes asistidos en el Hospital de Niños de Córdoba, con diagnóstico de HPC, de los cuales 42 (52%) presentaron PSIS; 22 mujeres y 20 varones, EC: 5 días-9,5 años. El 62% presentó MPHD y el 38% insuficiencia somatotrófica aislada (IGHD). El análisis de las variables perinatales demostró antecedentes de parto natural en el 52% (11/21) de las MPHD vs. 13% (2/15) de las IGHD. Cuatro pacientes, 2 con MPHD y 2 con IGHD presentaban antecedentes obstétricos consistentes en presentación podálica y transversa respectivamente, todos ellos resueltos mediante operación cesárea. Los signos y los síntomas perinatales fueron hipo- glucemia: 61% en MPHD vs. 19% en IGHD, p: 0,0105; ictericia: 38% en MPHD vs. 25% en IGHD; micropene: 77% en MPHD y colestasis: 19% en MPHD. Convulsiones neonatales se presentaron en el 75% de los niños con MPHD e hipoglucemia. EC media de consulta: 2,1 años en MPHD (30% en el período neonatal, 70% antes de 2 años) y 3,6 años en IGHD (44% en menores de 2 años). Los pacientes con MPHD presentaban: tallo no visible 81% (n: 21/26) vs. tallo hipoplásico: 19% (n: 5/26), p: 0,0001; en IGHD 56% (n: 9/16) vs. 44% (n: 7/16), p: 0,5067, respectivamente. El 100% de los neonatos con HPC tenían tallo pituitario ausente. Concluimos que la demostración de PSIS en niños con HPC proporciona información valiosa como predictor de la severidad fenotípica, la presencia de MPHD y de la respuesta al tratamiento. La baja frecuencia de antecedentes obstétricos posicionales potencialmente distócicos, como parte de los mecanismos fisiopatogénicos responsables de PSIS, indicaría la necesidad de analizar la importancia de posibles factores genéticos y epigenéticos involucrados. El diagnóstico precoz de HPC debe sospecharse en presencia de signos y síntomas clínicos, tales como hipoglucemia, colestasis, micropene y defectos asociados en la línea media facial. La resonancia magnética cerebral debe formar parte de los estudios complementarios en pacientes con esta presunción diagnóstica, especialmente a edades tempranas. El reconocimiento tardío de esta entidad puede aumentar la morbilidad y la mortalidad con efectos potenciales deletéreos y permanentes.

Pituitary stalk interruption syndrome (PSIS) is characterised by the combination of an interrupted or thin pituitary stalk, absent or ectopic posterior pituitary, and anterior pituitary hypoplasia. It is manifested as isolated (IGHD) or combined pituitary hormone deficiencies (CPHD) of variable degrees and timing of onset, with a wide spectrum of clinical phenotypes. PSIS may be an isolated morphological abnormality or be part of a syndrome. A retrospective evaluation is presented of clinical signs and symptoms present at early life stages, as well as an analysis of their relationship with hormone laboratory tests and diagnostic imaging in children with congenital hypopituitarism (CHP), and PSIS. This study was performed in a single centre on a sample of 42 children out of a total of 80 CHP patients, with a chronological age range between 5 days and 9.5 years from a database analysed over a period of 26 years. The study included 26/42 (62%) with CPHD and 16/42 (38%) with IGHD. The analysis of perinatal variables showed a natural delivery in 52% (11/21) of CPHD vs 13% (2/15) of IGHD. Four patients, two with CPHD and two IGHD had breech and transverse presentation respectively. All of them were resolved by caesarean section. The perinatal histories showed hypoglycaemia (61% CPHD vs 19% IGHD, P=.0105), jaundice (38% CPHDvs25% IGHD), micropenis (75%CPHD), hypoglycaemic seizures (75% CPHD), and cholestasis (19% CPHD). The mean CA of consulting for CPHD patients was 2.1 years, 30% in neonatal period and 70% before 2 years. The mean chronical age (CA) was 3.6 years in IGHD patients, with 44% of them less than 2 years. MRI showed that 81% of CPHD patients had absence of pituitary stalk vs 19% with thin pituitary stalk (P=.0001); Patients with IGHD presented 56% absence of pituitary stalk vs 44% with thin pituitary stalk (P=.5067). All (100%) of the patients diagnosed in the neonatal stage had absent pituitary stalk. The characterisation of GH deficient patients by presence and type of hypothalamic-pituitary imaging abnormality provides valuable information as a predictor of phenotypic severity, treatment response, and the potential to develop additional hormonal deficiencies. We conclude that demonstrating PSIS in children with HPC provides valuable information as a predictor of phenotypic severity, presence of MPHD, and response to treatment. The low frequency of potentially dysfunctional positional obstetric history, as part of the pathophysiological mechanisms responsible for PSIS, would indicate the need to analyse the importance of possible genetic and epigenetic factors involved. Early diagnosis of HPC should be suspected in the presence of clinical signs and symptoms, such as hypoglycaemia, cholestasis, micropenis, and associated facial midline defects. MRI should be part of complementary studies in patients with this diagnostic suspicion, especially at an early age. Late recognition of this entity may increase morbidity and mortality with potential permanent deleterious effects.

Molecular analysis of brazilian patients with combined pituitary hormone deficiency and orthotopic posterior pituitary lobe reveals eight different PROP1 alterations with three novel mutations.

BACKGROUND: Mutations in PROP1, HESX1 and LHX3 are associated with combined pituitary hormone deficiency (CPHD) and orthotopic posterior pituitary lobe (OPP). OBJECTIVE: To identify mutations in PROP1, HESX1 and LHX3 in a large cohort of patients with CPHD and OPP (35 Brazilian, two Argentinian). DESIGN AND METHODS: We studied 23 index patients with CPHD and OPP (six familial and 17 sporadic) as well as 14 relatives. PROP1 was sequenced by the Sanger method in all except one sporadic case studied using a candidate gene panel. Multiplex ligation-dependent probe amplification (MLPA) was applied to one familial case in whom PROP1 failed to amplify by PCR. In the 13 patients without PROP1 mutations, HESX1 and LHX3 were sequenced by the Sanger method. RESULTS: We identified PROP1 mutations in 10 index cases. Three mutations were novel: one affecting the initiation codon (c.1A>G) and two affecting splicing sites, c.109+1G>A and c.342+1G>C. The known mutations, c.150delA (p.Arg53Aspfs*112), c.218G>A (p.Arg73His), c.263T>C (p.Phe88Ser) and c.301_302delAG (p.Leu102Cysfs*8), were also detected. MLPA confirmed complete PROP1 deletion in one family. We did not identify HESX1 and LHX3 mutations by Sanger. CONCLUSION: PROP1 mutations are a prevalent cause of congenital CPHD with OPP, and therefore, PROP1 sequencing must be the first step of molecular investigation in patients with CPHD and OPP, especially in populations with a high frequency of PROP1 mutations. In the absence of mutations, massively parallel sequencing is a promising approach. The high prevalence and diversity of PROP1 mutations is associated with the ethnic background of this cohort.

Compound heterozygous DUOX2 gene mutations (c.2335-1G>C/c.3264_3267delCAGC) associated with congenital hypothyroidism. Characterization of complex cryptic splice sites by minigene analysis.

Iodide Organification defects (IOD) represent 10% of cases of congenital hypothyroidism (CH) being the main genes affected that of TPO (thyroid peroxidase) and DUOX2 (dual oxidasa 2). From a patient with clinical and biochemical criteria suggestive with CH associated with IOD, TPO and DUOX2 genes were analyzed by means of PCR-Single Strand Conformation Polymorphism analysis and sequencing. A novel heterozygous compound to the mutations c.2335-1G>C (paternal mutation, intron 17) and c.3264_3267delCAGC (maternal mutation, exon 24) was identified in the DUOX2 gene. Ex-vivo splicing assays and subsequent RT-PCR and sequencing analyses were performed on mRNA isolated from the HeLa cells transfected with wild-type and mutant pSPL3 expression vectors. The wild-type and c.2335-1G>C mutant alleles result in the complete inclusion or exclusion of exon 18, or in the activation of an exonic cryptic 5' ss with the consequent deletion of 169 bp at the end of this exon. However, we observed only a band of the expected size in normal thyroid tissue by RT-PCR. Additionally, the c.2335-1G>C mutation activates an unusual cryptic donor splice site in intron 17, located at position -14 of the authentic intron 17/exon 18 junction site, with an insertion of the last 14 nucleotides of the intron 17 in mutant transcripts with complete and partial inclusion of exon 18. The theoretical consequences of splice site mutation, predicted with the bioinformatics NNSplice, Fsplice, SPL, SPLM and MaxEntScan programs were investigated and evaluated in relation with the experimental evidence. These analyses confirm that c.2335-1G>C mutant allele would result in the abolition of the authentic splice acceptor site. The results suggest the coexistence in our patient of four putative truncated proteins of 786, 805, 806 and 1105 amino acids, with conservation of peroxidase-like domain and loss of gp91(phox)/NOX2-like domain. In conclusion a novel heterozygous compound was identified being responsible of IOD. Cryptic splicing sites have been characterized in DUOX2 gene for the first time. The use of molecular biology techniques is a valuable tool for understanding the molecular pathophysiology of this type of thyroid defects.

Effect of the parental origin of the X-chromosome on the clinical features, associated complications, the two-year-response to growth hormone (rhGH) and the biochemical profile in patients with turner syndrome.

BACKGROUND: It is possible that genes on the X chromosome are expressed differently depending of its parental origin. The objective of this study was to determine the influence of the parental origin of the X-chromosome on phenotypic variability, response to rhGH and on the biochemical profile of TS patients. METHODS: This was a cross-sectional multicenter correlational study carried out over three years in six Latin-American university hospitals. Unrelated 45,X TS patients (n = 93; 18.3 ± 8.5 years )) were evaluated. A subgroup (n = 34) of the patients were prospectively treated with rhGH over two years. DNA profiles of patients and their mothers were compared to determine the parental origin of the retained X-chromosome through 10 polymorphic X-chromosome-STRs. The association with clinical features, biochemical profiles and anthropometric data at the beginning and after two years of rhGH treatment was determined. RESULTS: Seventy two percent of patients retained the maternal X chromosome (Xm). A trend towards significance between maternal height and patients final height (p ≤ 0.07) in 45,Xm subjects was observed. There was no correlation between paternal height and patient height. No differences were detected between both groups in regard to dysmorphic features, classical malformations or increase in the height-SDS after rhGH. There were higher levels of triglycerides, total and LDL cholesterol in patients >20 years who retained the Xm. CONCLUSIONS: The parental origin of the retained X chromosome may influence lipid metabolism in TS patients, but its effect on growth seems to be minimal. No parental-origin-effect on the phenotypic features, associated anomalies and on the growth response to rhGH was found in 45,X TS individuals.

New insights into thyroglobulin gene: molecular analysis of seven novel mutations associated with goiter and hypothyroidism.

The thyroglobulin (TG) gene is organized in 48 exons, spanning over 270 kb on human chromosome 8q24. Up to now, 62 inactivating mutations in the TG gene have been identified in patients with congenital goiter and endemic or non-endemic simple goiter. The purpose of the present study was to identify and characterize new mutations in the TG gene. We report 13 patients from seven unrelated families with goiter, hypothyroidism and low levels of serum TG. All patients underwent clinical, biochemical and imaging evaluation. Single-strand conformation polymorphism (SSCP) analysis, endonuclease restriction analysis, sequencing of DNA, genotyping, population screening, and bioinformatics studies were performed. Molecular analyses revealed seven novel inactivating TG mutations: c.378C>A [p.Y107X], c.2359C>T [p.R768X], c.2736delG [p.R893fsX946], c.3842G>A [p.C1262Y], c.5466delA [p.K1803fsX1833], c.6000C>G [p.C1981W] and c.6605C>G [p.P2183R] and three previously reported mutations: c.886C>T [p.R277X], c.6701C>A [p.A2215D] and c.7006C>T [p.R2317X]. Six patients from two families were homozygous for p.R277X mutation, four were compound heterozygous mutations (p.Y107X/p.C1262Y, p.R893fsX946/p.A2215D, p.K1803fsX1832/p.R2317X), one carried three identified mutations (p.R277X/p.C1981W-p.P2183R) together with a hypothetical micro deletion and the remaining two siblings from another family with typical phenotype had a single p.R768X mutated allele. In conclusion, our results confirm the genetic heterogeneity of TG defects and the pathophysiological importance of altered TG folding as a consequency of truncated TG proteins and missense mutations located in ACHE-like domain or that replace cysteine.

Association of vitamin D receptor gene Cdx2 polymorphism with bone markers in Turner syndrome patients.

BACKGROUND: Turner syndrome (TS) patients usually have low bone mineral density (BMD) and increased risk of osteoporotic fractures. We have previously demonstrated an association of bb (BsmI polymorphic site) and ff (FokI polymorphic site) vitamin D receptor (VDR) genotypes with reduced BMD in TS patients. AIM: To analyze the relationship between VDR-Cdx2 polymorphism and BMD as well as bone metabolic variables in TS patients. METHODS: Fifty-five TS patients and 59 control women were studied. VDR-Cdx2 genotypes were determined using TaqMan probes in a real time thermocycler. Lumbar and femoral BMD were determined by dual-energy X-ray absorptiometry (DEXA) and serum intact parathyroid hormone, osteocalcin and beta3-CrossLaps were determined by electrochemiluminescence. RESULTS: Patients with genotype GG had higher levels of both osteocalcin and beta-CrossLaps as compared to patients with genotype GA (p < 0.01 and p < 0.05, respectively). CONCLUSION: Patients carrying genotype GG have higher levels of bone formation and resorption markers. This indicates a more active bone turnover that could impact on their future bone mineral density.

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. OBJECTIVES: 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.