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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Congenital hypothyroidism is a relatively common endocrine disorder, affecting one in 4000 newborn infants. Undiagnosed and untreated congenital hypothyroidism will result in un-toward consequences, including mental retardation and other significant neurologic sequelae. For these reasons, programs to screen newborns were developed to detect congenital hypothyroidism before clinical features become obvious enough to suggest the diagnosis. The most common clinical features include prolonged jaundice, skin mottling, hypotonia, umbilical hernia, constipation, and macroglossia. Congenital hypothyroidism may be caused by several different disorders; ectopic thyroid glands represent the most common cause. There is accumulating evidence that autoimmune thyroid disease as manifested by TBII may be the cause of thyroid dysgenesis in some cases. The diagnosis is easily confirmed by finding a low serum free T4 or total T4 and elevated serum TSH concentration. The treatment of choice is levothyroxine; these infants must be followed carefully to ensure normal growth and development and maintenance of serum T4 and TSH within the normal ranges. With appropriate treatment and follow-up, the large majority of these infants have an excellent prognosis, with an IQ no different from comparison populations. However, it appears that there is still a small percentage of infants who are the most severely affected, who manifest the lowest serum T4 levels, thyroid aplasia, and retarded bone ages, and who may run the highest risk for some degree of retardation and other neurologic sequelae. Acquired hypothyroidism is also a relatively common disorder, occurring in one in 500 to one in 1000 school-age children. These children most commonly have a slowdown in growth, short stature, a goiter, and a drop in school performance. Other clinical features may be subtle or absent except in more severe or long-standing cases. The most common cause is chronic lymphocytic thyroiditis. The diagnosis is easily established by finding low serum-free T4 or total T4 and elevated serum TSH concentrations. Again, levothyroxine is the treatment of choice. With appropriate treatment and follow-up, all clinical features that develop after age 3 should be reversible and the prognosis should therefore be very good.
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PMID:Diagnosis and treatment of hypothyroidism in children. 331 7

Congenital hypothyroidism is the commonest endocrine disorder of childhood. Early thyroxine therapy will ameliorate or prevent the considerable physical and mental retardation that is the hallmark of infantile hypothyroidism, and evidence is presented that a neonatal screening programme for thyroid hormones will reveal evidence of primary thyroid hypofunction (1/4 500 births) in infants prior to clinical diagnosis.
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PMID:Congenital hypothyroidism. Clinicopathological aspects and biochemical screening. 701 10

Endocrine disorders associated with mental retardation are described in relation to clinical characteristics, pathogenesis, diagnostic procedures, and treatment. Some endocrine disorders, particularly hypothyroidism, nephrogenic-diabetes insipidus, and hypoglycemic conditions, are frequently associated with mental retardation. Early diagnosis and prompt and proper management reduce mortality and the incidence of mental retardation associated with endocrine disorders.
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PMID:Endocrine disorders associated with mental retardation. 739 67

Congenital hypothyroidism is the most prevalent endocrine disorder in the newborn and affects 1 in 3000-4000 newborns. Screening for congenital hypothyroidism is a major achievement of paediatrics because early diagnosis and treatment have resulted in normal development in nearly all cases. The cause of congenital hypothyroidism in the majority of newborns is unknown. However, in some patients the molecular basis of their congenital hypothyroidism has recently been clarified. In patients with congenital hypothyroidism and a normally developed thyroid gland, the autosomal recessive inheritance of loss-of-function mutations of genes encoding for the thyroid peroxidase gene, the sodium-iodide symporter gene and the pendrin gene have been identified. The autosomal recessive inheritance of loss-of-function mutations of the thyroid stimulating hormone (TSH) receptor as well as the dominant inheritance of mutations encoding for transcription factors have been identified in patients with defective thyroid development. Furthermore, it has become evident that in some patients with persistent mental retardation and neurological symptoms, defects of the transcription factor NKX2.1, which is expressed in the thyroid gland as well as in the CNS during embryonic development, cause both defective thyroid and CNS development resulting in persistent neurological and mental defects despite early diagnosis and treatment. Central hypothyroidism is a rare disease with an estimated frequency of not more than 1 in 50000 newborns. Central hypothyroidism can be due to recessive inheritance of loss-of-function mutations of the TSH-beta gene and to developmental defects of the hypothalamus or pituitary. In contrast to the previous assumption that isolated TSH deficiency will not lead to impaired mental development, identification of the molecular defects in central hypothyroidism has clearly demonstrated that some of these patients will have impaired mental development. Clarification of the molecular defects of thyroid development will help to explain the differences in outcome in patients with congenital hypothyroidism and to develop new diagnostic and therapeutic strategies to ensure adequate counselling and care for these patients.
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PMID:Neonatal thyroid disorders. 1256 17

Congenital hypothyroidism is the most common congenital endocrine disorder (one newborn in 3000) and represents the most common cause of preventable mental retardation. In 10-20% of cases, it is due to autosomal recessive functional disorders leading to goiter formation (thyroid dyshormonogenesis). In the remainder, it is due to thyroid dysgenesis, which comprises usually isolated defects in: (1) migration of the median thyroid anlage, leading to a round cluster of ectopic cells (usually in a sublingual position) with no other thyroid tissue present; (2) differentiation or survival of the thyroid follicular cells leading to athyreosis; and (3) growth of a thyroid with the normal bilobed shape and in the normal cervical position (orthotopic hypoplasia). Mouse knock-outs have demonstrated that thyroid transcription factor-1 (TTF-1) and PAX8 are required for the survival and proliferation of thyroid follicular cell precursors, TTF-2 for their downward migration and the thyrotropin receptor (TSHR) for post-natal thyroid growth. In humans, thyroid dysgenesis is generally a sporadic malformation but an affected relative is found in 2% of cases, a figure 15-fold higher than by chance alone. Pedigree analysis is most compatible with dominant inheritance with variable penetrance. However, mutations in TTF-1, TTF-2, PAX8 and TSHR are found in <10% of patients with congenital hypothyroidism and these predominantly have orthotopic thyroid hypoplasia, often associated with other malformations. This low yield and the discordance of >90% of monozygotic twin pairs suggests that isolated thyroid ectopy or athyreosis most often results from early somatic mutations, epigenetic modifications or stochastic developmental events.
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PMID:Development of the thyroid gland: lessons from congenitally hypothyroid mice and men. 1278 49

Congenital hypothyroidism is the most frequent endocrine disorder in neonates. Controversy exists regarding the necessity to adjust current screening programs to also diagnose patients with central hypothyroidism or those with mild forms of congenital hypothyroidism, who have high TSH levels but normal T(4) and normal T(3) levels (also known as 'subclinical hypothyroidism'). Thyroid hormone replacement should start as soon as the diagnosis is confirmed by measurement of elevated TSH and low serum thyroid hormone levels. Further diagnostic approaches, such as ultrasonography, scintigraphy and measurement of thyroglobulin levels, to determine the subtype of congenital hypothyroidism, should not delay initiation of treatment. Recommendations regarding the initial dosage of levothyroxine vary considerably, and no general accepted guideline exists with regards to initial dosage or optimal time point for dose adjustment according to biochemical parameters. More than 30 years after the introduction of the first neonatal screening programs, mental retardation can be prevented in the majority of children (>90%) with congenital hypothyroidism if therapy is commenced within the first 2 weeks of life, making neonate screening for this disorder the most successful population-based screening test in pediatrics.
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PMID:Detection and treatment of congenital hypothyroidism. 2200 63

Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder and results in mental retardation if untreated. Eighty-five percent of CH cases are due to disruptions in thyroid organogenesis and are mostly sporadic, but about 2% of thyroid dysgenesis is familial, indicating the involvement of genetic factors in the aetiology of the disease. In this study, we aimed to investigate the Mendelian (single-gene) causes of non-syndromic and non-goitrous congenital hypothyroidism (CHNG) in consanguineous or multi-case families. Here we report the results of the second part (n=105) of our large cohort (n=244), representing the largest such cohort in the literature, and interpret the overall results of the whole cohort. Additionally, 50 sporadic cases with thyroid dysgenesis and 400 unaffected control subjects were included in the study. In familial cases, first, we performed potential linkage analysis of four known genes causing CHNG (TSHR, PAX8, TSHB, and NKX2-5) using microsatellite markers and then examined the presence of mutations in these genes by direct sequencing. In addition, in silico analyses of the predicted structural effects of TSHR mutations were performed and related to the mutation specific disease phenotype. We detected eight new TSHR mutations and a PAX8 mutation but no mutations in TSHB and NKX2-5. None of the biallelic TSHR mutations detected in familial cases were present in the cohort of 50 sporadic cases. Genotype/phenotype relationships were established between TSHR mutations and resulting clinical presentations. Here we conclude that TSHR mutations are the main detectable cause of autosomal recessively inherited thyroid dysgenesis. We also outline a new genetic testing strategy for the investigation of suspected autosomal recessive non-goitrous CH.
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PMID:TSHR is the main causative locus in autosomal recessively inherited thyroid dysgenesis. 2287 33

Congenital hypothyroidism (CH) is the most common congenital endocrine disorder, with an incidence of 1:2,000 to 1:4,000 live births and it is a leading preventable mental retardation. Neonatal Screening Programs allow early identification of the disease and the adequate treatment of affected children can avoid the complications related to deprivation of the hormone. Most cases of primary congenital hypothyroidism (85%) are due to thyroid dysgenesis (ectopia, hypoplasia or agenesis) while the remaining result from defects in hormone synthesis. Affected children (> 95%) usually have no symptoms suggesting the disease at birth. The most frequent symptoms and signs are prolonged neonatal jaundice, hoarse cry, lethargy, slow movements, constipation, macroglossia, umbilical hernia, large fontanelle, hypotonia and dry skin. Around the world, various strategies are used for the screening of the CH. In Brazil, screening for CH is mandatory by law and usually done by serum TSH in dried blood collected from the heel. The recommended age for performing this test is after 48 hours of life until the 4th day. Diagnostic confirmation is required dosing TSH and free T4 or total T4 in serum.
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PMID:Congenital hypothyroidism: recommendations of the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism. 2368 Dec 64

The most common congenital endocrine disorder is congenital hypothyroidism (CH), which can lead to mental retardation if untreated. Majority of the patients have been found to have defects in thyroid development and migration disorders (dysgenesis), and the remaining ones have thyroid hormone synthesis defects (dyshormonogenesis). One of the most common mechanisms to cause dyshormonogenesis is a defect in the thyroid peroxidase (TPO) enzyme. In familial cases, mutations in the TPO gene are fairly prevalent. To date, more than 80 mutations have been identified, which result in variably decreasing TPO bioactivities. Clinical manifestations of TPO defects are typically permanent CH and with or without goiter. In this report, we presented two children with CH who were born to consanguineous parents and were homozygous carriers of a missense (G319R) TPO mutation, the mutation segregated with the disease status in the families confirming its pathogenicity. G319R mutation seemed to be a common cause of CH in Turkish population, which could originate from a common founder ancestor. Moreover, our results also confirmed the phenotypic variability associated with different TPO mutations.
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PMID:A common thyroid peroxidase gene mutation (G319R) in Turkish patients with congenital hypothyroidism could be due to a founder effect. 2415 20

The dance of Siva has a cosmic appeal. Nowhere has this dance been crystallised in its pristine form as in the Nataraja Bronzes from the Chola period. Mysticism surrounds the dancing form of the Nataraja. But does Nataraja dance upon an endocrine mystery. Does the demon under his feet Apasmara literally forgetfulness or epilepsy have an endocrine disorder. The short limbed stocky eye popping dwarf with possible mental retardation with a name that suggests epilepsy throws open a host of endocrine diagnoses. From cretinisim to the original descriptions of pseudohypoparathyroidism here is one view of the medical mystery under Shiva's dancing feet.
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PMID:Endocrinology and the arts at the feet of the dancing Lord: Parathyroid hormone resistance in an Indian icon. 2474 22


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