Congenital Central Hypothyroidism Research Articles

Identification of a Novel IGSF1 Variant in Two Malaysian Male Siblings with Central Hypothyroidism and Macroorchidism.

IGSF1 mutation is the commonest cause of mild to moderate isolated central congenital hypothyroidism and has an X-linked recessive inheritance, primarily affecting males. Other notable clinical features are macroorchidism with delayed pubertal testosterone rise, large birth weight, increased body mass index, low prolactin, transient growth hormone deficiency and low prolactin. Two male siblings with central hypothyroidism were found to have a novel IGSF1 c.3467T>A variant that was likely pathogenic based on the family segregation study. The proband, aged 3 years presented at 18 days old with prolonged jaundice while his 16-year-old brother was only detected to have central hypothyroidism after the proband's genetic analysis result was known. Both siblings were obese, had large birth weights, macroorchidism and low prolactin. The proband's brother had intellectual disability while the proband had normal development. This case study highlights the importance of evaluation for the IGSF1 variant in patients with unexplained central hypothyroidism, especially when accompanied by X-linked inheritance and macroorchidism. Family segregation analysis allows detection of other affected family members or carriers who may also benefit from thyroxine treatment.

Mutant Tbl1x male mice have a short life span and do not breed: unexpected findings.

Humans with the mutation Y509C in transducin beta like 1 X-linked (TBL1X HGNC ID HGNC:11585) have been reported to present with the combination of central congenital hypothyroidism and impaired hearing. TBL1X belongs to the WD40 repeat-containing protein family, is part of NCoR and SMRT corepressor complexes, and thereby involved in thyroid hormone signaling. In order to investigate the effects of the Y509C mutation in TBL1X on cellular thyroid hormone action, we aimed to generate a hemizygous male mouse cohort carrying the Tbl1x Y459C mutation which is equivalent to the human TBL1X Y509C mutation using CRISPR/Cas9 technology. Hemizygous male mice were small at birth and inactive. Their life span (median life span 93 days) was very short compared with heterozygous female mice (survived to >200 days with no welfare issues). About 52% of mice did not survive to weaning (133 mice). Of the remaining 118 mice, only 8 were hemizygous males who were unable to mate whereby it was impossible to generate homozygous female mice. In conclusion, the Tbl1x Y459C mutation in male mice has a marked negative effect on birth weight, survival, and fertility of male mice. The present findings are unexpected as they are in contrast to the mild phenotype in human males carrying the equivalent TBL1X Y509C mutation.

The hypothalamic-pituitary-thyroid axis is intact in male insulin receptor substrate 4 knockout mice.

Loss of function mutations in the insulin receptor substrate 4 (IRS4) gene cause a rare form of X-linked congenital central hypothyroidism in boys and men. Affected individuals show decreased thyroid-stimulation hormone (TSH) secretion. Members of the IRS family canonically act as scaffold proteins between tyrosine kinase receptors and downstream effectors. How loss of IRS4 affects TSH synthesis or secretion is unresolved. We therefore assessed IRS4's role in the hypothalamic-pituitary-thyroid axis of Irs4 knockout mice. We generated two global Irs4 knockout mouse lines harboring either two or four base-pair deletions that result in frameshifts and loss of most of the IRS4 protein. Under normal laboratory conditions, Irs4 knockout males did not exhibit impairments in pituitary expression of TSH subunit genes (Tshb or Cga) or in the thyrotropin-releasing hormone (TRH) receptor. Additionally, their serum thyroid hormone, T3 (triiodothyronine) and T4 (thyroxine), and hypothalamic Trh expression levels were normal. When Irs4 knockouts were rendered hypothyroid with a low-iodine diet supplemented with propylthiouracil (PTU) for 3 weeks, their serum TSH increased similarly to wild-type males. Overall, Irs4 knockout mice do not exhibit central hypothyroidism or otherwise appear to phenocopy IRS4 deficient patients. Compensation by another IRS protein may explain euthyroidism in these animals.

Clinical and molecular analyses of isolated central congenital hypothyroidism based on a survey conducted in Japan.

Central congenital hypothyroidism (CH) can occur as an isolated deficiency or as part of combined pituitary hormone deficiency. Unlike primary CH, central CH cannot be detected by newborn screening (NBS) using dry filter paper blood TSH levels, and early diagnosis remains challenging. In this study, the clinical and genetic backgrounds of patients with isolated central CH were determined through a questionnaire-based survey among members of the Japanese Society for Pediatric Endocrinology. The known causes of isolated central CH were studied in 14 patients, including six with previously reported patient data. The results revealed IGSF1 and TBL1X pathogenic variants in nine and one patient, respectively. All six patients with low free thyroxine (FT4) levels detected in NBS carried IGSF1 pathogenic variants. Five patients with isolated central CH diagnosed after 3 months of age were variant-negative, except for one female patient with a heterozygous IGSF1 variant. Two of the four variant-negative patients and a variant-positive patient were diagnosed with pituitary hypoplasia. One and two patients with IGSF1 variant had obesity and intellectual disability, respectively. Left amblyopia was identified in the patient with a TBL1X variant. The study revalidated that IGSF1 variants comprise the most frequent pathogenic variant in patients with isolated central CH in Japan. The neonatal period is the optimal time for the diagnosis of central CH, particularly IGSF1 abnormalities, and the introduction of T4 screening should be considered in the future, taking cost-effectiveness into consideration.

Optimizing the Dutch newborn screening for congenital hypothyroidism by incorporating amino acids and acylcarnitines in a machine learning-based model.

Congenital hypothyroidism (CH) is an inborn thyroid hormone (TH) deficiency mostly caused by thyroidal (primary CH) or hypothalamic/pituitary (central CH) disturbances. Most CH newborn screening (NBS) programs are thyroid-stimulating-hormone (TSH) based, thereby only detecting primary CH. The Dutch NBS is based on measuring total thyroxine (T4) from dried blood spots, aiming to detect primary and central CH at the cost of more false-positive referrals (FPRs) (positive predictive value (PPV) of 21% in 2007-2017). An artificial PPV of 26% was yielded when using a machine learning-based model on the adjusted dataset described based on the Dutch CH NBS. Recently, amino acids (AAs) and acylcarnitines (ACs) have been shown to be associated with TH concentration. We therefore aimed to investigate whether AAs and ACs measured during NBS can contribute to better performance of the CH screening in the Netherlands by using a revised machine learning-based model. Dutch NBS data between 2007 and 2017 (CH screening results, AAs and ACs) from 1079 FPRs, 515 newborns with primary (431) and central CH (84) and data from 1842 healthy controls were used. A random forest model including these data was developed. The random forest model with an artificial sensitivity of 100% yielded a PPV of 48% and AUROC of 0.99. Besides T4 and TSH, tyrosine, and succinylacetone were the main parameters contributing to the model's performance. The PPV improved significantly (26-48%) by adding several AAs and ACs to our machine learning-based model, suggesting that adding these parameters benefits the current algorithm.

Normal intellectual ability and hyperprolactinemia as unique clinical manifestations of congenital hypothyroidism: A case report and review of hypotheses.

Congenital hypothyroidism is the deficiency of thyroid hormone in infants and hyperprolactinemia is frequently observed. Previously reported cases typically involve intellectual disability, highlighting this particular unique case report to the first reported patient demonstrating normal intellectual ability despite experiencing growth and gonad dysfunction. This study aims to present a case and review medical hypotheses related to the patient's condition. A 19-year-old female presented with a chief complaint of irregular menstruation for up to 40 days or not occurring at all. The patient experienced the first menstruation at the age of 16 years old. The patient's height was 133 cm, body weight 40 kg, and body mass index 22.61 kg/m2; other family members were normal. Physical examination showed no abnormalities, and laboratory examination showed suppressed serum free T4 (FT4) level (6.41 pmol/L), elevated thyroid stimulating hormone (TSH) level (333.700 µIU/mL), and elevated prolactin hormone level (32.03 ng/mL). Ultrasound of the thyroid gland found hypoplasia of the left and right thyroid glands. The patient was a college student enrolled in a public national university and had never complained about academic performance throughout the patient's education. The patient was diagnosed with congenital hypothyroidism and hyperprolactinemia. The patient was administered up to 100 µg daily of oral levothyroxine, which improved the patient's menstrual cycles. The patient's delayed diagnosis may be attributed to central congenital hypothyroidism being underdiagnosed. We hypothesized that thyroid-releasing hormone receptor (TRHR) gene mutation might contribute to the underlying cause of hyperprolactinemia and normal intellectual ability of the patient. Further study on the significance of TRHR gene mutations in congenital hypothyroidism is required to improve diagnosis and treatment.

Genetic Basis of Congenital Central Hypothyroidism in Children: Expanding the Mutational Spectrum of POU1F1 and ATP6V0A4.

Congenital central hypothyroidism (CCH) is a rare disorder poorly described in childhood and adolescence. The current knowledge on the genetic bases of CCH is scarce. The purpose of this study was to analyze the clinical characteristics and molecular genetic basis of CCH in children. We conducted a thorough evaluation of the clinical features in children diagnosed with CCH. Genomic DNA was extracted from peripheral blood of both children and their parents, and chromosomal microarray analysis and whole-exome sequencing were performed. Candidates for single nucleotide variants were validated using Sanger sequencing and were classified according to the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) guidelines. Two cases with likely pathogenic variants were detected by whole-exome sequencing. Individual 1 carried a novel homozygous ATP6V0A4 c.1418C>T (p.Ser473Phe) variant and a novel heterozygous POU1F1 c.416G>A. (p.Arg139Gln) variant. Individual 2 had a novel homozygous POU1F1 c.212C>T (p.Ala71Val) variant. The chromosomal microarray detected the presence of a 24 Mb heterozygous deletion (LOH: loss of heterozygosity) in the p12.1p13.13 region of chromosome 2 in individual 3, and the copy number variant was unknown of clinical significance. Our study employed chromosomal microarray and whole-exome sequencing to investigate central hypothyroidism in seven children, leading to the detection of genetic anomalies in three individuals. The identification of novel variants has contributed to the expanded genetic spectrum of POU1F1 and ATP6V0A4 associated with pediatric central hypothyroidism.

Neonatal screening for primary and central congenital hypothyroidism: is it time to go Dutch?

Thyroid hormone (TH) is indispensable for brain development in utero and during the first two to three years of life, and the negative effects of TH deficiency on brain development are irreversible. Detection of TH deficiency early in life by neonatal screening allows early treatment, thereby preventing brain damage. Inborn shortage of TH, also named congenital hypothyroidism (CH), can be the result of defective thyroid gland development or TH synthesis (primary or thyroidal CH (CH-T)). Primary CH is characterized by low blood TH and elevated thyroid-stimulating hormone (TSH) concentrations. Less frequently, CH is due to insufficient stimulation of the thyroid gland because of disturbed hypothalamic or pituitary function (central CH). Central CH is characterised by low TH concentrations while TSH is normal, low or slightly elevated. Most newborn screening (NBS) programs for CH are primarily TSH-based thereby do not detect central CH. Only a few NBS programs worldwide aim to detect both forms of CH by different strategies. In the Netherlands, we have a unique T4-TSH-thyroxine-binding globulin (TBG) NBS algorithm for CH which enables detection of primary and central CH. Although the necessity of central CH detection by NBS is still under debate, it has been shown that most central CH patients have moderate-to-severe hypothyroidism instead of mild, and that early detection of central CH by NBS problably improves its clinical outcome and clinical care for central CH patients with multiple pituitary hormone deficiency. We are therefore convinced that detection of central CH by NBS is of utmost importance.

Hepatomegaly and fatty liver disease secondary to central hypothyroidism in combination with macrosomia as initial presentation of IGSF1 deficiency syndrome.

IGSF1 deficiency syndrome (immunoglobulin superfamily member 1) is considered the most common sex-linked cause of secondary congenital hypothyroidism and is characterized by a wide variety of other clinical and biochemical features, including hypoprolactinemia, transient and partial growth hormone deficiency, early/normal timing of testicular enlargement but delayed testosterone rise in puberty, and adult macro-orchidism. Congenital central hypothyroidism is a rare disease (1:65,000 births); the detection of which may be delayed and missed by neonatal screening programs since most neonatal screening programs are based on TSH determination in dried blood spots only. Untreated hypothyroidism may cause abnormal liver biochemistry and non-alcoholic fatty liver disease. Our aim is to report a case of secondary hypothyroidism in an infant with an uncommon initial presentation. A 3-month-old male baby was referred to our hospital due to elevated alpha-fetoprotein levels, hypercholesterolemia, and macrosomia. Initial investigations revealed enlarged fatty liver and central hypothyroidism. Pituitary insufficiency was biochemically excluded and a pituitary MRI showed normal findings. Upon genetic analysis, a hemizygous variant NM_001170961.1:c.2422dup, p.(His808Profs*14), in IGSF1 gene was detected, establishing the diagnosis of the IGSF1 deficiency syndrome. In our patient, no other clinical findings were identified. Treatment with levothyroxine led to the remission of liver disease. Liver disease may be the initial presentation of secondary hypothyroidism in neonates and infants. Macrosomia in patients with isolated secondary central hypothyroidism is a strong indicator of IGSF1 syndrome.

A Rare Case of Congenital Hypothyroidism

Congenital Hypothyroidism (CH) is a common preventable cause of mental retardation. The incidence of CH is 1 in 2500 to 1 in 3000 newborns. Most common causes are thyroid dysgenesis and dyshormonogenesis. Some disorder like maternal autoantibodies, maternal intake of anti thyroid medication, iodine deficiency or iodine excess can result in transient CH. Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice. In this case report, A 3 day old baby was admitted to SNCU with chief complain of yellowish discoloration upto abdomen and respiratory distress. On examination, common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia. Thyroid dysgenesis accounts for 85% of permanent, primary CH, while inborn errors of thyroid hormone biosynthesis (dyshormonogeneses) account for 10-15% of cases. Secondary or central CH may occur with isolated TSH deficiency, but more commonly it is associated with congenital hypopitiutarism. Transient CH most commonly occurs in preterm infants born.

[Clinical characteristics and genetic analysis of four patients with central hypothyroidism due to IGSF1 gene variants].

To explore the clinical manifestations and genetic characteristics of patients with congenital central hypothyroidism due to variants of IGSF1 gene. Clinical data, results of genetic testing, and follow-up of four patients admitted to Children's Hospital of Soochow University during 2017 to 2021 were retrospectively analyzed. All of the four patients were males. Patient 1 had presented neonatal jaundice, patients 2 and 3 were admitted for growth retardation during childhood, and thyroid function test indicated slightly low free thyroxine (FT4), patient 4 was found to have reduced FT4 in the neonatal period. Genetic testing revealed that all of the four patients have harbored pathogenic variants of the IGSF1 gene, which were all inherited from their mothers. The thyroid functions in all patients were well controlled with oral levothyroxine and regular follow-up. Pathogenic variants of the IGSF1 gene probably underlay the congenital central hypothyroidism with a variety of clinical manifestations, and genetic testing can facilitate the diagnosis at an early stage.

Machine learning to improve false-positive results in the Dutch newborn screening for congenital hypothyroidism

ObjectiveThe Dutch Congenital hypothyroidism (CH) Newborn Screening (NBS) algorithm for thyroidal and central congenital hypothyroidism (CH-T and CH-C, respectively) is primarily based on determination of thyroxine (T4) concentrations in dried blood spots, followed by thyroid-stimulating hormone (TSH) and thyroxine-binding globulin (TBG) measurements enabling detection of both CH-T and CH-C, with a positive predictive value (PPV) of 21%. A calculated T4/TBG ratio serves as an indirect measure for free T4. The aim of this study is to investigate whether machine learning techniques can help to improve the PPV of the algorithm without missing the positive cases that should have been detected with the current algorithm. Design & methodsNBS data and parameters of CH patients and false-positive referrals in the period 2007–2017 and of a healthy reference population were included in the study. A random forest model was trained and tested using a stratified split and improved using synthetic minority oversampling technique (SMOTE). NBS data of 4668 newborns were included, containing 458 CH-T and 82 CH-C patients, 2332 false-positive referrals and 1670 healthy newborns. ResultsVariables determining identification of CH were (in order of importance) TSH, T4/TBG ratio, gestational age, TBG, T4 and age at NBS sampling. In a Receiver-Operating Characteristic (ROC) analysis on the test set, current sensitivity could be maintained, while increasing the PPV to 26%. ConclusionsMachine learning techniques have the potential to improve the PPV of the Dutch CH NBS. However, improved detection of currently missed cases is only possible with new, better predictors of especially CH-C and a better registration and inclusion of these cases in future models.

ODP529 Update on the Prevalence and Pathogenesis of Central Hypothyroidism

Abstract Background Central hypothyroidism (CH) is a rare form of hypothyroidism characterized by insufficient stimulation of a normal thyroid gland by the thyroid-stimulating hormone (TSH). It can be of pituitary origin (secondary hypothyroidism) or hypothalamic origin (tertiary hypothyroidism). The diagnosis is suspected by the finding of low serum free thyroxine associated with low, normal, or slightly elevated serum TSH, in the absence of goiter. This review presents an update on the prevalence and pathogenesis of different types of CH. Methods A systematic search of literature was conducted using the search terms hypothyroidism, central hypothyroidism, congenital central hypothyroidism, acquired central hypothyroidism, TSH deficiency, prevalence, and pathogenesis. Results The prevalence of overt hypothyroidism in the US population is at least 0.3% and the prevalence of subclinical hypothyroidism ranges from 4% to 10%. Primary hypothyroidism is more prevalent in females. The prevalence of CH ranges from 1: 13,000 to 1: 120,000. CH is observed in less than 1% of hypothyroid subjects, with no evidence of sex predominance. Itcan occur prenatally (congenital CH) or after birth (acquired CH). Congenital CH, which is a rare cause of CH (prevalence around 1: 13,000), may result from genetic/malformative causes [e. g., pituitary-specific transcription factor defects, TSH-beta subunit gene mutations, isolated TSH-releasing hormone (TRH) deficiency, TRH receptor gene mutation, immunoglobulin superfamily member 1 deficiency, De Morsier syndrome, Prader Willi syndrome]. In 60% of the cases, congenital CH is associated with other pituitary hormone deficiencies and in 40% of the cases, congenital CH is due to isolated TSH deficiency. Acquired CH, which is the most common cause of CH andusually associated with other pituitary hormone deficiencies, results from the destruction or inhibition of the pituitary and/or hypothalamus. In decreasing order of frequency, acquired CH can be secondary to invasive and/or compressive lesions (e. g., pituitary macroadenomas, craniopharyngiomas, pituitary metastases, carotid aneurysm), iatrogenic factors (e. g., surgery or irradiation, glucocorticoids, dopaminergic drugs, somatostatin analogs, immune checkpoint inhibitors), trauma (e. g., brain injury), vascular causes (e. g., pituitary apoplexy, postpartum pituitary necrosis, hemorrhage), autoimmunity (e. g., lymphocytic hypophysitis), infiltrative lesions (e. g., hemochromatosis, sarcoidosis), and infections (e. g., tuberculosis, syphilis). Conclusion CH is a rare cause of hypothyroidism resulting from a variety of congenital or acquired causes. Acquired CH is the most common cause of CH. In many cases, both congenital and acquired CH are associated with multiple pituitary hormone deficiencies. Isolated TSH deficiency is rare and usually of congenital origin. Presentation: No date and time listed

Maternal hypothyroidism is associated with M-opsin developmental delay.

Thyroid hormones are critical for the development of opsins involved in color vision. Hypothyroid mice show delayed M-opsin development and expanded distribution of S-opsin on the retina. However, the effects of maternal hypothyroidism on opsin development remain unknown. This study investigates the effects of congenital central hypothyroidism and maternal hypothyroidism on opsin development in thyrotropin-releasing hormone knockout (TRH-/-) mice. We examined the mRNA expression and protein distribution of S/M-opsin on postnatal days (P)12 and 17, as well as mRNA expression of type 2 and 3 iodothyronine deiodinase (DIO2 and DIO3, respectively) in the retina and type 1 iodothyronine deiodinase (DIO1) in the liver at P12 in TRH+/- mice born to TRH+/- or TRH-/- dams, and conducted S/M-opsin analysis in TRH+/+ or TRH-/- mice born to TRH+/- dams at P12, P17, and P30. M-opsin expression was lower in TRH+/- mice born to TRH-/- dams than in those born to TRH+/- dams, whereas S-opsin expression did not significantly differ between them. DIO1, DIO2, and DIO3 mRNA expression levels were not significantly different between the two groups; therefore, thyroid function in peripheral tissues in the pups was similar. S/M-opsin expression did not significantly differ between the TRH+/+ and TRH-/- mice born to TRH+/- dams on any postnatal day. These results demonstrate that maternal hypothyroidism causes M-opsin developmental delay during the early developmental stages of neonatal mice, and TRH-/- mice, a model of congenital central hypothyroidism, born to a euthyroid dam do not have delayed opsin development.

Novel TSHB variant (c.217A>C) causing severe central hypothyroidism and pituitary hyperplasia.

SummaryBiallelic pathological variants in the thyroid stimulating hormone (TSH) subunit β gene (TSHB) result in isolated TSH deficiency and secondary hypothyroidism, a rare form of central congenital hypothyroidism (CCH), with an estimated incidence of 1 in 65 000 births. It is characterised by low levels of free thyroxine and inappropriately low serum TSH and may therefore be missed on routine neonatal screening for hypothyroidism, which relies on elevated TSH. We describe a patient with CCH who developed recurrence of pituitary hyperplasia and symptomatic hypothyroidism due to poor compliance with thyroxine replacement. She was diagnosed with CCH as a neonate and had previously required trans-sphenoidal hypophysectomy surgery for pituitary hyperplasia associated with threatened chiasmal compression at 17 years of age due to variable adherence to thyroxine replacement. Genetic testing of TSHB identified compound heterozygosity with novel variant c.217A>C, p.(Thr73Pro), and a previously reported variant c.373delT, p.(Cys125Valfs*10). Continued variable adherence to treatment as an adult resulted in recurrence of significant pituitary hyperplasia, which subsequently resolved with improved compliance without the need for additional medications or repeat surgery. This case describes a novel TSHB variant associated with CCH and demonstrates the importance of consistent compliance with thyroxine replacement to treat hypothyroidism and prevent pituitary hyperplasia in central hypothyroidism.Learning pointsPathogenic variants in the TSH subunit β gene (TSHB) are rare causes of central congenital hypothyroidism (CCH).c.217A>C, p.(Thr73Pro), is a novel TSHB variant, presented in association with CCH in this case report.Thyroxine replacement is critical to prevent clinical hypothyroidism and pituitary hyperplasia.Pituitary hyperplasia can recur post-surgery if adherence to thyroxine replacement is not maintained.Pituitary hyperplasia can dramatically reverse if compliance with thyroxine replacement is improved to maintain free thyroxine (FT4) levels in the middle-to-upper normal range, without the need for additional medications or surgeries.

The extant immunoglobulin superfamily, member 1 gene results from an ancestral gene duplication in eutherian mammals

Immunoglobulin superfamily, member 1 (IGSF1) is a transmembrane glycoprotein with high expression in the mammalian pituitary gland. Mutations in the IGSF1 gene cause congenital central hypothyroidism in humans. The IGSF1 protein is co-translationally cleaved into N- and C-terminal domains (NTD and CTD), the latter of which is trafficked to the plasma membrane and appears to be the functional portion of the molecule. Though the IGSF1-NTD is retained in the endoplasmic reticulum and has no apparent function, it has a high degree of sequence identity with the IGSF1-CTD and is conserved across mammalian species. Based upon phylogenetic analyses, we propose that the ancestral IGSF1 gene encoded the IGSF1-CTD, which was duplicated and integrated immediately upstream of itself, yielding a larger protein encompassing the IGSF1-NTD and IGSF1-CTD. The selective pressures favoring the initial gene duplication and subsequent retention of a conserved IGSF1-NTD are unresolved.

Genetics of congenital hypothyroidism: Modern concepts.

ABSTRACTCongenital hypothyroidism (CH) is the most common neonatal endocrine disorder and one of the most common preventable causes of intellectual disability in the world. CH may be due to developmental or functional thyroid defects (primary or peripheral CH) or be hypothalamic‐pituitary in origin (central CH). In most cases, primary CH is caused by a developmental malformation of the gland (thyroid dysgenesis, TD) or by a defect in thyroid hormones synthesis (dyshormonogenesis, DH). TD represents about 65% of CH and a genetic cause is currently identified in fewer than 5% of patients. The remaining 35% are cases of DH and are explained with certainty at the molecular level in more than 50% of cases. The etiology of CH is mostly unknown and may include contributions from individual and environmental factors. In recent years, the detailed phenotypic description of patients, high‐throughput sequencing technologies, and the use of animal models have made it possible to discover new genes involved in the development or function of the thyroid gland. This paper reviews all the genetic causes of CH. The modes by which CH is transmitted will also be discussed, including a new oligogenic model. CH is no longer simply a dominant disease for cases of CH due to TD and recessive for cases of CH due to DH, but a far more complex disorder.

Congenital central hypothyroidism diagnosed in-utero

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Génétique de l’hypothyroïdie congénitale

Congenital hypothyroidism (CH) is the most frequent neonatal endocrine disorder. CH is due to thyroid development or thyroid function defects (primary) or may be of hypothalamic-pituitary origin (central). Primary CH is caused essentially by abnormal thyroid gland morphogenesis (thyroid dysgenesis, TD) or defective thyroid hormone synthesis (dyshormonogenesis, DH). DH accounts for about 35% of CH and a genetic cause is identified in 50% of patients. However, TD accounts for about 65% of CH, and a genetic cause is identified in less than 5% of patients. The pathogenesis of CH is largely unknown and may include the contribution of individual and environmental factors. During the last years, detailed phenotypic description of patients, next-generation sequence technologies and use of animal models allowed the discovery of novel candidate genes in thyroid development and function. We provide an overview of recent genetic causes of primary and central CH. In addition, mode of inheritance and the oligogenic model of CH are discussed.

A novel nonsense variant (p.Arg1293Ter) of the immunoglobulin superfamily 1 (IGSF1) associated with congenital hypogonadotropic hypogonadism and central hypothyroidism.

A novel nonsense variant (p.Arg1293Ter) of the immunoglobulin superfamily 1 (IGSF1) associated with congenital hypogonadotropic hypogonadism and central hypothyroidism.