|
Thyroid Dyshormonogenesis
Thyroid dyshormonogenesis is a rare condition due to genetic defects in the synthesis of thyroid hormones. It is due to either deficiency of thyroid enzymes, inability to concentrate, or ineffective binding. Signs and symptoms The symtptoms of this disease are: Very Frequent * Decreased circulating thyroxine level * Elevated circulating TSH concentration Frequent * Abnormality of epiphysis * Congenital hypothyroidism * Constipation * Delayed closure of the cranial suture. * Delay of proximal femoral epiphyseal ossification * Feeding difficulties * Goitre * Big posterior fontanelle * Neurodevelopmental problems * Neonatal jaundice * Umbilical hernia Occasional * Abnormality of circulating thyroglobulin concentration * Slow heart rate * Saddle nose deformity * Edema of face * Decreased reflexes * Hypotonia * Hypothermia * Increase of radioactive iodine uptake * Mental handicap * Large tongue * Neonatal hyperbilirubinemia Very Rare * Sensorineural hearing loss Cause Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroid Hormones
File:Thyroid_system.svg, upright=1.5, The thyroid system of the thyroid hormones T3 and T4 rect 376 268 820 433 Thyroid-stimulating hormone rect 411 200 849 266 Thyrotropin-releasing hormone rect 297 168 502 200 Hypothalamus rect 66 216 386 256 Anterior pituitary gland rect 66 332 342 374 Negative feedback rect 308 436 510 475 Thyroid gland rect 256 539 563 635 Thyroid hormones rect 357 827 569 856 Catecholamine rect 399 716 591 750 Metabolism desc bottom-left Thyroid hormones are two hormones produced and released by the thyroid gland, triiodothyronine (T3) and thyroxine (T4). They are tyrosine-based hormones that are primarily responsible for regulation of metabolism. T3 and T4 are partially composed of iodine, derived from food. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre. The major form of thyroid hormone in the blood is thyroxine (T4), whose half-life of arou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensorineural Deafness
Sensorineural hearing loss (SNHL) is a type of hearing loss in which the root cause lies in the inner ear, sensory organ (cochlea and associated structures), or the vestibulocochlear nerve (Cranial nerves, cranial nerve VIII). SNHL accounts for about 90% of reported hearing loss. SNHL is usually permanent and can be mild, moderate, severe, profound, or total. Various other descriptors can be used depending on the shape of the audiogram, such as high frequency, low frequency, U-shaped, notched, peaked, or flat. ''Sensory'' hearing loss often occurs as a consequence of damaged or deficient cochlear hair cells. Hair cells may be abnormal at birth or damaged during the lifetime of an individual. There are both external causes of damage, including Ear infection, infection, and Ototoxicity, ototoxic drugs, as well as intrinsic causes, including genetic mutations. A common cause or exacerbating factor in SNHL is prolonged exposure to environmental noise, or noise-induced hearing loss. Ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pendred's Syndrome
Pendred syndrome is a genetic disorder leading to congenital bilateral (both sides) sensorineural hearing loss and goitre with euthyroid or mild hypothyroidism (decreased thyroid gland function). There is no specific treatment, other than supportive measures for the hearing loss and thyroid hormone supplementation in case of hypothyroidism. It is named after Vaughan Pendred (1869–1946), the British doctor who first described the condition in an Irish family living in Durham in 1896. It accounts for 7.5% to 15% of all cases of congenital deafness. Signs and symptoms The hearing loss of Pendred syndrome is often, although not always, present from birth, and language acquisition may be a significant problem if deafness is severe in childhood. The hearing loss typically worsens over the years, and progression can be step-wise and related to minor head trauma. In some cases, language development worsens after head injury, demonstrating that the inner ear is sensitive to trauma in Pend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OMIM
Online Mendelian Inheritance in Man (OMIM) is a continuously updated catalog of human genes and genetic disorders and traits, with a particular focus on the gene-phenotype relationship. , approximately 9,000 of the over 25,000 entries in OMIM represented phenotypes; the rest represented genes, many of which were related to known phenotypes. Versions and history OMIM is the online continuation of Victor A. McKusick's ''Mendelian Inheritance in Man'' (MIM), which was published in 12 editions between 1966 and 1998.McKusick, V. A. ''Mendelian Inheritance in Man. Catalogs of Autosomal Dominant, Autosomal Recessive and X-Linked Phenotypes.'' Baltimore, MD: Johns Hopkins University Press, 1st ed, 1996; 2nd ed, 1969; 3rd ed, 1971; 4th ed, 1975; 5th ed, 1978; 6th ed, 1983; 7th ed, 1986; 8th ed, 1988; 9th ed, 1990; 10th ed, 1992. Nearly all of the 1,486 entries in the first edition of MIM discussed phenotypes. MIM/OMIM is produced and curated at the Johns Hopkins School of Medicine ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SLC5A5
The sodium/iodide cotransporter, also known as the sodium/iodide symporter (NIS), is a protein that in humans is encoded by the ''SLC5A5'' gene. It is a transmembrane glycoprotein with a molecular weight of 87 k Da and 13 transmembrane domains, which transports two sodium cations (Na+) for each iodide anion (I−) into the cell. NIS mediated uptake of iodide into follicular cells of the thyroid gland is the first step in the synthesis of thyroid hormone. Iodine uptake Iodine uptake mediated by thyroid follicular cells from the blood plasma is the first step for the synthesis of thyroid hormones. This ingested iodine is bound to serum proteins, especially to albumins. The rest of the iodine which remains unlinked and free in bloodstream, is removed from the body through urine (the kidney is essential in the removal of iodine from extracellular space). Iodine uptake is a result of an active transport mechanism mediated by the NIS protein, which is found in the basolateral membran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroid Peroxidase
Thyroid peroxidase, also called thyroperoxidase (TPO), thyroid specific peroxidase or iodide peroxidase, is an enzyme expressed mainly in the thyroid where it is secreted into colloid. Thyroid peroxidase oxidizes iodide ions to form iodine atoms for addition onto tyrosine residues on thyroglobulin for the production of thyroxine (T4) or triiodothyronine (T3), the thyroid hormones. In humans, thyroperoxidase is encoded by the ''TPO'' gene. Function Inorganic iodine enters the body primarily as iodide, I−. After entering the thyroid follicle (or thyroid follicular cell) via a Na+/I− symporter (NIS) on the basolateral side, iodide is shuttled across the apical membrane into the colloid via pendrin after which thyroid peroxidase oxidizes iodide to atomic iodine (I) or iodinium (I+). The chemical reactions catalyzed by thyroid peroxidase occur on the outer apical membrane surface and are mediated by hydrogen peroxide. The "organification of iodine", the incorporation of iodine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SLC26A4
Pendrin is an anion exchange protein that in humans is encoded by the ''SLC26A4'' gene (solute carrier family 26, member 4). Pendrin was initially identified as a sodium-independent chloride-iodide exchanger with subsequent studies showing that it also accepts formate and bicarbonate as substrates. Pendrin is similar to the Band 3 transport protein found in red blood cells. Pendrin is the protein which is mutated in Pendred syndrome, which is an autosomal recessive disorder characterized by sensorineural hearing loss, goiter and a partial organification problem detectable by a positive perchlorate test. Pendrin orthologs are responsible for mediating the electroneutral exchange of chloride (Cl−) for bicarbonate (HCO3−) across a plasma membrane in the chloride cells of freshwater fish, and show changes in expression in response to salinity change in the gills of Atlantic stingrays. By phylogenetic analysis, pendrin has been found to be a close relative of prestin present on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroglobulin
Thyroglobulin (Tg) is a 660 kDa, dimeric glycoprotein produced by the follicular cells of the thyroid and used entirely within the thyroid gland. Tg is secreted and accumulated at hundreds of grams per litre in the extracellular compartment of the thyroid follicles, accounting for approximately half of the protein content of the thyroid gland. Human TG (hTG) is a homodimer of subunits each containing 2768 amino acids as synthesized (a short signal peptide of 19 amino acids may be removed from the N-terminus in the mature protein). Thyroglobulin is in all vertebrates the main precursor to thyroid hormones, which are produced when thyroglobulin's tyrosine residues are combined with iodine and the protein is subsequently cleaved. Each thyroglobulin molecule contains approximately 16 tyrosine residues, but only around 10 of these are subject to iodination by thyroperoxidase in the follicular colloid. It takes two iodinated tyrosines to make a thyroid hormone molecule; therefor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodotyrosine Deiodinase
Iodotyrosine deiodinase, also known as iodotyrosine dehalogenase 1, is a type of deiodinase enzyme that scavenges iodide by removing it from iodinated tyrosine residues in the thyroid gland. These iodinated tyrosines are produced during thyroid hormone biosynthesis. The iodide that is scavenged by iodotyrosine deiodinase is necessary to again synthesize the thyroid hormones. After synthesis, the thyroid hormones circulate through the body to regulate metabolic rate, protein expression, and body temperature. Iodotyrosine deiodinase is thus necessary to keep levels of both iodide and thyroid hormones in balance. Dehalogenation in aerobic organisms is usually done through Redox, oxidation and hydrolysis; however, iodotyrosine deiodinase uses reductive dehalogenation. Iodotyrosine deiodinase and iodothyronine deiodinase have been determined as the only two known enzymes to catalyze reductive dehalogenation in mammals. Although these two enzymes perform similar functions, they are st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DUOX2
Dual oxidase 2, also known as DUOX2 or ThOX2 (for thyroid oxidase), is an enzyme that in humans is encoded by the ''DUOX2'' gene. Dual oxidase is an enzyme that was first identified in the mammalian thyroid gland. In humans, two isoforms are found; hDUOX1 and hDUOX2 (this enzyme). The protein location is not exclusive to thyroid tissue; hDUOX1 is prominent in airway epithelial cells and hDUOX2 in the salivary glands and gastrointestinal tract. Function Investigations into reactive oxygen species ( ROS) in biological systems have, until recently, focused on characterization of phagocytic cell processes. It is now well accepted that production of such species is not restricted to phagocytic cells and can occur in eukaryotic non-phagocytic cell types via NADPH oxidase (NOX) or dual oxidase (DUOX). This new family of proteins, termed the NOX/DUOX family or NOX family of NADPH oxidases, consists of homologs to the catalytic moiety of phagocytic NADPH-oxidase, gp91phox. Members of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Levothyroxine
Levothyroxine, also known as -thyroxine, is a synthetic form of the thyroid hormone thyroxine (T4). It is used to treat thyroid hormone deficiency (hypothyroidism), including a severe form known as myxedema coma. It may also be used to treat and prevent certain types of thyroid tumors. It is not indicated for weight loss. Levothyroxine is taken orally (by mouth) or given by intravenous injection. Levothyroxine has a half-life of 7.5 days when taken daily, so about six weeks is required for it to reach a steady level in the blood. Side effects from excessive doses include weight loss, trouble tolerating heat, sweating, anxiety, trouble sleeping, tremor, and fast heart rate. Use is not recommended in people who have had a recent heart attack. Use during pregnancy has been found to be safe. Dosing should be based on regular measurements of thyroid-stimulating hormone (TSH) and T4 levels in the blood. Much of the effect of levothyroxine is following its conversion to tri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
