Guy Van Vliet

European Society for Paediatric Endocrinology Consensus Guidelines on Screening, Diagnosis, and Management of Congenital Hypothyroidism

Objective: The aim was to formulate practice guidelines for the diagnosis and management of congenital hypothyroidism (CH). Evidence: A systematic literature search was conducted to identify key articles relating to the screening, diagnosis, and management of CH. The evidence-based guidelines were developed with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. Consensus Process: Thirty-two participants drawn from the European Society for Paediatric Endocrinology and five other major scientific societies in the field of pediatric endocrinology were allocated to working groups with assigned topics and specific questions. Each group searched the literature, evaluated the evidence, and developed a draft document. These papers were debated and finalized by each group before presentation to the full assembly for further discussion and agreement. Recommendations: The recommendations include: worldwide neonatal screening, approaches to assess the cause (including genotyping) and the severity of the disorder, the immediate initiation of appropriate L-T4 supplementation and frequent monitoring to ensure dose adjustments to keep thyroid hormone levels in the target ranges, a trial of treatment in patients suspected of transient CH, regular assessments of developmental and neurosensory functions, consulting health professionals as appropriate, and education about CH. The harmonization of diagnosis, management, and routine health surveillance would not only optimize patient outcomes, but should also facilitate epidemiological studies of the disorder. Individuals with CH require monitoring throughout their lives, particularly during early childhood and pregnancy.

Mutations in FGF17, IL17RD, DUSP6, SPRY4, and FLRT3 Are Identified in Individuals with Congenital Hypogonadotropic Hypogonadism

Congenital hypogonadotropic hypogonadism (CHH) and its anosmia-associated form (Kallmann syndrome [KS]) are genetically heterogeneous. Among the >15 genes implicated in these conditions, mutations in FGF8 and FGFR1 account for ~12% of cases; notably, KAL1 and HS6ST1 are also involved in FGFR1 signaling and can be mutated in CHH. We therefore hypothesized that mutations in genes encoding a broader range of modulators of the FGFR1 pathway might contribute to the genetics of CHH as causal or modifier mutations. Thus, we aimed to (1) investigate whether CHH individuals harbor mutations in members of the so-called FGF8 synexpression group and (2) validate the ability of a bioinformatics algorithm on the basis of protein-protein interactome data (interactome-based affiliation scoring [IBAS]) to identify high-quality candidate genes. On the basis of sequence homology, expression, and structural and functional data, seven genes were selected and sequenced in 386 unrelated CHH individuals and 155 controls. Except for FGF18 and SPRY2, all other genes were found to be mutated in CHH individuals: FGF17 (n = 3 individuals), IL17RD (n = 8), DUSP6 (n = 5), SPRY4 (n = 14), and FLRT3 (n = 3). Independently, IBAS predicted FGF17 and IL17RD as the two top candidates in the entire proteome on the basis of a statistical test of their protein-protein interaction patterns to proteins known to be altered in CHH. Most of the FGF17 and IL17RD mutations altered protein function in vitro. IL17RD mutations were found only in KS individuals and were strongly linked to hearing loss (6/8 individuals). Mutations in genes encoding components of the FGF pathway are associated with complex modes of CHH inheritance and act primarily as contributors to an oligogenic genetic architecture underlying CHH.

Lethal respiratory failure and mild primary hypothyroidism in a term girl with a de novo heterozygous mutation in the TITF1/NKX2.1 gene.

CONTEXTnThyroid transcription factor 1 (TITF1/NKX2.1) is expressed in the thyroid, lung, ventral forebrain, and pituitary. In the lung, TITF1/NKX2.1 activates the expression of genes critical for lung development and function. Titf/Nkx2.1(-/-) mice have pituitary and thyroid aplasia but also impairment of pulmonary branching. Humans with heterozygous TITF1/NKX2.1 mutations present with various combinations of primary hypothyroidism, respiratory distress, and neurological disorders.nnnOBJECTIVEnThe objective of the study was to report clinical and molecular studies of the first patient with lethal neonatal respiratory distress from a novel heterozygous TITF1/NKX2.1 mutation.nnnPARTICIPANTnThis girl, the first child of healthy nonconsanguineous French-Canadian parents, was born at 41 wk. Birth weight was 3,460 g and Apgar scores were normal. Soon after birth, she developed acute respiratory failure with pulmonary hypertension. At neonatal screening on the second day of life, TSH was 31 mU/liter (N <15) and total T(4) 245 nmol/liter (N = 120-350). Despite mechanical ventilation, thyroxine, surfactant, and pulmonary vasodilators, the patient died on the 40th day.nnnRESULTSnHistopathology revealed pulmonary tissue with low alveolar counts. The thyroid was normal. Sequencing of the patients lymphocyte DNA revealed a novel heterozygous TITF1/NKX2.1 mutation (I207F). This mutation was not found in either parent. In vitro, the mutant TITF-1 had reduced DNA binding and transactivation capacity.nnnCONCLUSIONnThis is the first reported case of a heterozygous TITF1/NKX2.1 mutation leading to neonatal death from respiratory failure. The association of severe unexplained respiratory distress in a term neonate with mild primary hypothyroidism is the clue that led to the diagnosis.

Bioinactive ACTH Causing Glucocorticoid Deficiency

CONTEXTnA 4-year-old girl and a 4-month-old boy presented with hypoglycemia, normal electrolytes, low cortisol, and high ACTH. A diagnosis of primary adrenal insufficiency was made and initial treatment was with glucocorticoids and mineralocorticoids. The genes known to cause ACTH resistance were normal. Whole exome sequencing revealed that the girl was compound heterozygous for POMC mutations: one previously described null allele and one novel p.R8C mutation in the sequence encoding ACTH and α-MSH. The boy was homozygous for the p.R8C mutation.nnnHYPOTHESISnThe p.R8C ACTH mutant is immunoreactive, but the mutant peptides, ACTH-R8C and α-MSH-R8C, are bioinactive.nnnMETHODSnMethods included whole exome sequencing, Sanger sequencing, peptide synthesis, ACTH immunoradiometric assay, hormone binding, and activation assays in cells expressing melanocortin receptors.nnnRESULTSnACTH-R8C was immunoreactive but failed to bind and activate cAMP production in melanocortin-2 receptor (MC2R)-expressing cells, and α-MSH-R8C failed to bind and stimulate cAMP production in MC1R- and MC4R-expressing cells.nnnCONCLUSIONnThese are the first documented cases of glucocorticoid deficiency due to the secretion of an ACTH molecule that lacks biological bioactivity but conserves immunoreactivity. POMC mutations should thus be considered in patients presenting with apparent ACTH resistance. Our findings also highlight a limitation to immunoassay-based diagnostics and demonstrate the value of genetic analysis. Establishing the molecular etiology of the disorder in our patients allowed cessation of the unnecessary mineralocorticoids. Finally, discovery of this mutation indicates that in humans, the amino acid sequence His(6)Phe(7)Arg(8)Trp(9) is important not only for cAMP activation but also for ACTH binding to MC2R.

Severe Cortisol Deficiency Associated with Reversible Growth Hormone Deficiency in Two Infants: What Is the Link?

CONTEXTnHypoglycemia is potentially life-threatening, especially in infants, and can be due to congenital cortisol and/or GH deficiency (GHD).nnnCASE ILLUSTRATIONnTwo full-term infants had undetectable cortisol levels, but also low GH levels, at the time of severe hypoglycemia. GHD persisted for several months, even after cortisol replacement.nnnMETHODSnTargeted molecular investigations were performed and revealed homozygous inactivating mutations in MRAP (MIM ID 609196) in patient 1 and in TPIT (MIM ID 604614) in patient 2. Because GHD is not part of the MRAP or TPIT phenotypes, we performed GH stimulation tests. These revealed that GHD had resolved by 8 months (patient 1) and 3 yr (patient 2) of glucocorticoid replacement. GH replacement was therefore stopped, hypoglycemia did not recur, and over the subsequent 10 yr, growth and puberty have proceeded normally.nnnCONCLUSIONSn1) Physiological glucocorticoid levels appear to be required for the development and function of the somatotrophs during infancy. 2) Eucortisolism, like euthyroidism, is required for the proper evaluation of GH secretory capacity. 3) The metabolic effect of GH replacement is essential for the maintenance of normoglycemia, especially in infants. And 4) targeted molecular investigations are a powerful tool to clarify the diagnosis in severely ill infants and to reevaluate the specific treatment they need.

Role for Tissue-Dependent Methylation Differences in the Expression of FOXE1 in Nontumoral Thyroid Glands

BACKGROUNDnDiscordance of monozygotic twins for thyroid dysgenesis suggests that epigenetic mechanisms may underlie defects in thyroid gland development. This prompted us to evaluate whether differentially methylated regions (DMRs) can be found between human thyroids (either eutopic or ectopic) and matched leukocytes.nnnMETHODSnTo compare the genome-wide methylation profile of thyroids and leukocytes, immunoprecipitated methylated DNA was interrogated on human promoter plus CpG island tiling arrays. In addition, the methylation profile of the human FOXE1, PAX8, and NKX2.1 promoter was examined using bisulfite sequencing. Finally, the functional impact of CpG methylation of the promoter on FOXE1 expression was assessed with luciferase assays.nnnRESULTSnGenome-wide methylation profiling and bisulfite sequencing of CpG islands of PAX8 and NKX2.1 promoters revealed no DMR between thyroid and leukocytes. However, bisulfite sequencing revealed that the methylation level of two consecutive CpG dinucleotides (CpG14 and CpG15, which were not covered by the genome-wide array) in one CpG island of the FOXE1 promoter (-1600 to -1140 from the transcription start site) is significantly higher in leukocytes than in eutopic or ectopic thyroid tissues, suggesting that methylation of this region may decrease FOXE1 gene expression. Indeed, luciferase activities were decreased when FOXE1 promoter constructs were methylated in vitro. Moreover, derepression of luciferase activity was observed when the methylation of CpG14 and CpG15 was prevented by mutations.nnnCONCLUSIONnWe report a tissue-dependent DMR in the FOXE1 promoter. This DMR contains two consecutive CpG dinucleotides, which are epigenetic modifiers of FOXE1 expression in nontumoral tissues.

Impact of Patient Characteristics and Clinical Factors on the Decision to Initiate Growth Hormone Treatment in Turner Syndrome

Background/Aims: To evaluate factors contributing to the decision to initiate treatment with growth hormone (GH) in patients with Turner syndrome (TS). Methods: Data collected included ethnicity, parents’ education and work status, mid-parental height, age at diagnosis, karyotype, pubertal development, clinical severity score, bone age, height SDS and ages when GH was proposed and initiated. Results: GH was proposed to 59 of 72 patients >6 years (82%), and of these 46 (78%) accepted. Reasons for not proposing GH included late diagnosis, good growth and loss to follow-up. GH-treated and untreated girls differed by age at diagnosis (mean ± SD: 6.8 ± 4.7 vs. 4.3 ± 5.1 years; p = 0.04), TS-specific height SDS (0.08 ± 0.81 vs. 066 ± 0.87; p = 0.01) and spontaneous puberty (5/46 vs. 4/26, p = 0.024). Mean age at which it was suggested to begin GH was 9.2 ± 2.9 years. Reasons for parental refusal of GH were not related to reimbursement issues since GH treatment is covered fully by our insurance plan but included concern with other medical issues, mental health problems and fear of injections or unknown side effects. Conclusion: GH treatment was not acceptable to all patients with TS.

Interpreting Minor Variations in Thyroid Function or Echostructure: Treating Patients, Not Numbers or Images.

Overt thyroid dysfunction is documented by serum thyrotropin or T4 concentrations are often ordered for nonspecific complaints and will by definition fall outside of the 95% reference range 5% of the time. In addition, most laboratories quote adult ranges, which are not necessarily applicable to young children, and regression toward the mean is common, justifying that the test be repeated before embarking on treatment. On the other hand, neck ultrasounds are frequently performed for diffuse goiter or non-thyroid conditions. Yet, an ultrasound is not required to make a diagnosis of Hashimoto thyroiditis and small cysts and nodules discovered incidentally often lead to unjustified concerns about neoplasia.

Conserved Telomere Length in Human Ectopic Thyroids: An Argument Against Premature Differentiation Causing Arrested Migration.

BACKGROUNDnIn humans, the cause of arrested migration of the median thyroid anlage resulting in an ectopic sublingual gland is unknown. These ectopic glands have a normal follicular architecture but their thyrotropin-induced growth is insufficient, leading to congenital hypothyroidism in the vast majority of affected subjects. We hypothesized that arrested migration is due to premature differentiation [reflected by decreased telomere length (TL)], as observed in neural tube defects in mice.nnnMETHODSnAbsolute TL and telomerase reverse transcriptase (hTERT) expression was measured in four ectopic and six orthotopic thyroids. TL was measured by quantitative polymerase chain reaction of genomic DNA, whereas hTERT expression was measured by quantitative polymerase chain reaction of total RNA.nnnRESULTSnThe mean±standard deviation TL (in kilobases per diploid genome) was 140.45±40.07 in ectopic and 97.50±30.48 in orthotopic thyroids (p=0.12). Expression of hTERT was quiescent in both ectopic and orthotopic thyroids.nnnCONCLUSIONSnCompared with orthotopic thyroids, TL shortening is not observed in ectopic thyroid tissues and, consequently, no compensatory hTERT expression was measured. This makes premature differentiation an unlikely cause of arrested migration and it suggests, indirectly, that ectopic thyroids are not at higher risk of cancer than orthotopic thyroids.