O. Asam. University of Houston, Clear Lake.
Choking becomes more likely 10 mg cialis mastercard erectile dysfunction market, vated order 20 mg cialis mastercard erectile dysfunction use it or lose it, the immune system may mistake portions of the especially with food that requires extensive chewing. Weakness • About 10% of those with MG also have thymomas, or may involve muscles of the arms, legs, neck, trunk, and benign tumors of the thymus gland. The thymus is a face, and affect the ability to lift objects, walk, hold the principal organ of the immune system, and researchers head up, and speak. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 777 Myasthenia Gravis Familial Familial inheritance of Myasthenia gravis. Heat, including heat from the sun, hot botulism, and inherited muscular dystrophies. MG causes characteristic changes in the electrical Infection and stress may worsen symptoms. Symptoms responses of muscles that may be observed with an elec- may vary from day to day and month to month, with tromyogram, which measures muscular response to elec- intervals of no weakness interspersed with a progressive trical stimulation. Symptoms include weak and shallow breathing, body to the acetylcholine receptor, though up to a quarter shortness of breath, pale or bluish skin color, and a rac- of MG patients will not have detectable levels. Myasthenic crisis is an emergency condition ray or chest computed tomography scan (CT scan) may requiring immediate treatment. Treatment and management While there is no cure for myasthenia gravis, there Pregnancy worsens MG in about one third of are a number of treatments that effectively control symp- women, has no effect in one third, and improves symp- toms in most people. About 12% of infants born to women with MG have neonatal myasthenia, a temporary Edrophonium (Tensilon) blocks the action of acetyl- but potentially life-threatening condition. It is caused by cholinesterase, prolonging the effect of acetylcholine and the transfer of maternal antibodies into the fetal circula- increasing strength. Symptoms include weakness, poor leads to a marked improvement in most people with MG. Loss of responsiveness and disease Diagnosis progression combine to eventually make pyridostigmine ineffective in tolerable doses in many patients. Myasthenia gravis is often diagnosed accurately by a careful medical history and a neuromuscular exam, but Thymectomy, or removal of the thymus gland, has several tests are used to confirm the diagnosis. Up to ditions causing worsening of bulbar and skeletal muscles 85% of people with MG improve after thymectomy, with must be considered, including drug-induced myasthenia, complete remission eventually seen in about 30%. The 778 GALE ENCYCLOPEDIA OF GENETIC DISORDERS Myasthenia Gravis Sporadic Sporatic occurance of Myathenia gravis in a family. Drugs include corticosteroids such as prednisone, A Medic-Alert card or bracelet provides an impor- and the non-steroids azathioprine (Imuran) and tant source of information to emergency providers about cyclosporine (Sandimmune). Plasma exchange may be performed to treat myas- thenic crisis or to improve very weak patients before thymectomy. In this procedure, blood plasma is Prognosis removed and replaced with purified plasma free of autoantibodies. It can produce a temporary improve- Most people with MG can be treated successfully ment in symptoms, but is too expensive for long-term enough to prevent their condition from becoming debili- treatment. In some cases, however, symptoms may worsen immunoglobulin therapy, is also used for myasthenic even with vigorous treatment, leading to generalized crisis. There is no known way to unknown reasons, this leads to symptomatic improve- prevent myasthenia gravis. It is also too expensive toms significantly in many patients, and relieves them for long-term treatment. Avoiding heat can help minimize symp- People with weakness of the bulbar muscles may toms. In more severe cases, it may be necessary to obtain Resources nutrition through a feeding tube placed into the stomach BOOKS (gastrostomy tube). Neuromuscular Some drugs should be avoided by people with MG Diseases: A Practical Approach to Diagnosis and Man- because they interfere with normal neuromuscular func- agement. Drugs to be avoided or used with caution include: PERIODICALS • Many types of antibiotics, including erythromycin, Drachman, D. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 779 ORGANIZATIONS There are many types of myopia. By far the most common form, physiologic myopia WEBSITES Immune Deficiency Foundation. This condition begins as physiologic myopia, but rather than stabilizing, the eye continues to enlarge at an abnor- Catherine L.
In most instances 5mg cialis with mastercard erectile dysfunction with diabetes, anencephaly nosis of anencephaly can also be detected through occurs as an isolated birth defect with the other organs maternal serum alpha-fetoprotein screening buy 5 mg cialis amex stress and erectile dysfunction causes. In approxi- of alpha-fetoprotein in the maternal blood is elevated mately 10% of cases, other malformations coexist with because of the leakage of this fetal protein into the anencephaly. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 89 Diagram of Anencephaly NORMAL INFANT ANENCEPHALIC INFANT Brain Brain Stem Brain Stem Infants born with anencephaly have either a severly underdeveloped brain or total brain absence. A portion of the brain stem usually protrudes through the skull, which also fails to develop properly. Affected infants are stillborn or die within the first few ORGANIZATIONS days of life. Stevenson, MD all enriched cereal grain flours have been fortified with folic acid. Prognosis Anencephaly is uniformly fatal at birth or soon IAngelman syndrome thereafter. Definition Resources Angelman syndrome (AS) is a genetic condition that PERIODICALS causes severe mental retardation, severe speech impair- Czeizel, A. Individuals with AS show evidence of delayed “Prevention of neural tube defects: results of the Medical development by 6–12 months of age. However, receptive language skills (listen- designated 15q11-13 (bands 11 through 13 on the long ing to and understanding the speech of others) and non- arm of chromosome 15). Imprinting is a chemical gait ataxia (a slow, unbalanced way of walking) and modification of DNA which acts as an “identification tag” tremulous movements of the limbs. Imprinted genes or chromosome regions are expressed or AS is also associated with a unique “happy” behav- not expressed depending on which parent transmitted the ior, which may be the best-known feature of the condi- chromosome. This may include frequent laughter or smiling, often 15q11-13 region (from the father) cause a different with no apparent stimulus. These characteristic behaviors led to the origi- nal name of this condition, the “Happy Puppet” The most common cause of AS is a small deletion syndrome. However, this name is no longer used as it (missing piece) in the maternally inherited chromosome is considered insensitive to AS individuals and their 15. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 91 UBE3A mutation Signs and symptoms In approximately 11% of AS cases, there is a muta- The first abnormalities noted in an infant with AS are tion within the maternally inherited UBE3A gene. All often delays in motor milestones (those related to physi- the genetic mechanisms leading to AS appear to compro- cal skills, such as sitting up or walking), muscular hypo- mise expression of this gene, which is located within the tonia (poor muscle tone), and speech impairment. This gene is considered to be the “crit- infants seem unaccountably happy and may exhibit fits of ical gene” responsible for AS, although its specific func- laughter. Uniparental disomy Seizures occur in 80% of children with AS, usually by three years of age. No major brain lesions are typi- Some cases of AS result from inheritance of both cally seen on cranial imaging studies. Additionally, children may have drooling, protrusion of the tongue, hyperactivity, Imprinting defect and a short attention span. Approximately 3% of AS cases result from an Many children have a decreased need for sleep and imprinting defect on the maternally inherited chromo- abnormal sleep/wake cycles. As noted above, imprinting is a chemical mod- in infancy and persist throughout childhood. Upon awak- ification to the DNA which serves as a marker indicating ening at night, children may become very active and the parent of origin and controls gene expression. Older children and Chromosome rearrangement adults are able to communicate by using gestures or com- munication boards (special devices bearing visual symbols Rarely, AS may be caused by chromosomal breaks corresponding to commonly used expressions or words). The Some individuals with AS caused by a deletion of breaks may occur as the result of a translocation (in the 15q11-q13 chromosomal region may have a lighter which two chromosomes break and exchange material) skin complexion than would be expected given their fam- or an inversion (in which a piece of a chromosome breaks ily background. The clinical diagnosis of AS is made on the basis of physical examination and medical and developmental Unknown mechanism(s) history. Confirmation requires specialized laboratory In about 8% of individuals with AS, no genetic cause testing. This may reflect misdiagnosis, or the There is no single laboratory test that can identify all presence of additional, unrecognized mechanisms lead- cases of AS.
At this time there is no treatment for should receive three particular diagnostic tests buy discount cialis 10mg erectile dysfunction treatment maryland. However discount cialis 10mg online erectile dysfunction pills free trial, exam called an electroretinogram is used to test the elec- good health care beginning in childhood can help many tric currents of the retina. An ultrasound is used to exam- people with BBS avoid other serious effects of this disor- ine the kidneys, as is an intravenous pyelogram (IVP). Researchers are actively exploring genetic causes, IVP is an x-ray assessment of kidney function. Treatment and management Resources Unless they have severe birth defects involving the BOOKS heart, kidneys, or liver, patients with BBS can have a “Bardet-Biedl Syndrome. Because BBS carriers also appear prone to kidney disease, parents and siblings of patients with BBS should ORGANIZATIONS take extra precautions. Executive Plaza 1, Suite 800, for kidney defects or cancer, as well as preventive health 11350 McCormick Rd. NW, #404, Washing- In order to conserve vision to the extent possible, ton, DC 20008. The Foundation WEBSITES Fighting Blindness, a support and referral group, offers “Bardet Biedl Syndrome. Though not life-threatening, learning disabilities and reproductive dysfunction need attention in order to max- Avis L. Affected people benefit greatly from special or vocational educa- tion, speech therapy, social skills training, and commu- nity support services. Some adult patients may never be able to live independently and may remain with their IBatten disease families. In these cases, families should plan future living arrangements in case the patients outlive their caregivers. Definition Genital abnormalities may require hormonal treat- Batten disease is a disorder of the nervous system ment or surgical attention. Patients include mental impairment, seizures, and loss of sight with genital and reproductive dysfunction may need and motor skills. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 139 appear to be more common in children living in Northern KEY TERMS Europe and Newfoundland, Canada. Lysosome—Membrane-enclosed compartment in Early symptoms of Batten disease include vision dif- cells, containing many hydrolytic enzymes; where ficulties and seizures. There may also be personality and large molecules and cellular components are bro- behavioral changes, slow learning, clumsiness, or stum- ken down. Over time, the children experience mental impair- Neuronal ceroid lipofuscinoses—A family of four ment, worsening seizures, and the complete loss of vision progressive neurological disorders. Batten disease, like other childhood forms of NCL, may first be suspected during an eye exam that displays Description a loss of certain cells. Because such cell loss can occur in Batten disease is characterized by an abnormal other eye diseases, however, the disorder cannot be diag- buildup of lipopigments—substances made up of fats and nosed by this sign alone. The Batten disease may refer the child to a neurologist, who compartments, called lysosomes, normally take in and will analyze the medical history and information from break down waste products and complex molecules for various laboratory tests. Diagnosis It is marked by vision failure and the loss of intellect and neurological functions, which begin in early childhood. Diagnostic tests used for Batten disease and other NCLs include: Batten disease is a form of a family of progressive neurological disorders known as neuronal ceroid lipofus- • Blood or urine tests that detect abnormalities that may cinoses (or NCLs). It is also known as Spielmeyer-Vogt- indicate Batten disease Sjögren-Batten disease, or juvenile NCL. There are three • Skin or tissue sampling, which can detect the buildup of other disorders in the NCL family: Jansky-Bielchowsky lipopigments in cells disease, late infantile neuronal ceroid lipofuscinosis, and Kufs disease (a rare adult form of NCL). Although these • Electroencephalogram, which displays electrical activ- disorders are often collectively referred to as Batten dis- ity within the brain that suggests a person has seizures ease, Batten disease is a single disorder. This means that it occurs when a child Treatment and management receives one copy of the abnormal gene from each par- ent. Batten disease results from abnormalities in gene There is no known treatment to prevent or reverse CLN3. This specific gene was identified by researchers the symptoms of Batten disease or other NCLs. Other medicines may be prescribed to Individuals with only one abnormal gene are known manage other symptoms associated with the disorder.
Selenium: No reported adverse side ef- Preparations fects with normal dosage of 200 micrograms order 2.5mg cialis impotence vs impotence, higher Bottled antioxidant formulae are available in a single doses may cause dizziness and nausea order 20mg cialis overnight delivery erectile dysfunction treatment by homeopathy. The United There are no known side effects associated with normal States Department of Agriculture (USDA) has established doses of alpha lipoic acid, cysteine, glutathione, or NAC. For instance, the Interactions USDA recommendation for vitamin C is 60 mg a day but natural healthcare practitioners commonly recommend Vitamin C: No known common adverse interactions 500 mg a day or more. Vitamin A: Women taking birth control whether it is being taken to treat or prevent a specific con- pills should consult with their doctors before taking extra dition. Vitamin E: Should not be used by persons specific antioxidants are: vitamin A, 5,000-15,000 IU; taking anti-coagulation drugs. Carotenoids: No known beta carotene, 15,000-25,000 IU; vitamin C, 250-1,500 negative interactions with other drugs. Bioflavonoids: mg; vitamin E, 30-400 IU; selenium, 50-400 micrograms; No known adverse interactions with other drugs. Coen- bioflavonoids, 100-500 mg; grape seed extract, 150-200 zyme Q10: No negative drug interactions yet reported. Resources Precautions Vitamin C: May interfere with some laboratory tests, BOOKS Balch, Dr. The Super Antioxidants: Why They Will including urinary sugar spilling for diabetics. Avery Publishing risk of hip fractures in postmenopausal women, but the Group, 1999. Natural Alternatives to Over-the-Counter known precautions are indicated for normal doses. John Wiley and Sons, cian should be consulted before taking daily doses of more 1999. Side effects “Antioxidant Vitamin E Reported to Strengthen Immune Sys- Vitamin C: Individual tolerances vary. A person may feel anxious without Atherosclerosis—A buildup of fatty substances in having an anxiety disorder. Also, a person facing a clear the inside of arteries, resulting in the restriction of and present danger or a realistic fear is not usually con- blood flow and hardening of the vessels. In addition, anxiety Macular degeneration—An eye disease resulting frequently occurs as a symptom in other categories of in a loss of central vision in both eyes while pe- psychiatric disturbance. Oxidation—The loss of electrons from a molecule Description by their bonding to an oxygen molecule, render- ing the donor molecule positive in charge and the Anxiety is related to fear, but it is not the same recipient oxygen negative in charge (free radical). Fear is a direct, focused response to a specific event or object of which an individual is consciously Sinusitis—An inflammation or infection in the aware. Whereas most people will be fearful in physically dan- “Lutein Helps Protect Eyes, Doctors Say in Survey. Anxiety is characterized by the following symp- “Vitamin A Intake Levels Reaffirmed as Safe and Beneficial. These physical symptoms include headaches, dizziness or lightheadedness, nausea and/or vomiting, Ken R. Odle ness, difficulty in breathing, and sensations of tightness in the chest, neck, shoulders, or hands. These symptoms are produced by the hormonal, muscular, and cardiovas- cular reactions involved in the fight-or-flight reaction. Behavioral symptoms of anxiety include Anxiety pacing, trembling, general restlessness, hyperventilation, Definition pressured speech, hand wringing, and finger tapping. Emotional symptoms include feelings of changes can produce anxious feelings as well as muscle tension or nervousness, feeling “hyper” or “keyed up,” tension and other physical symptoms of anxiety. Numerous sponses to stress or by certain disease processes or med- medications may cause anxiety-like symptoms as a side ications. They include birth control pills, some thyroid or THE AUTONOMIC NERVOUS SYSTEM (ANS). The ner- asthma drugs, some psychotropic agents, corticos- vous system of human beings is hard-wired to respond to teroids, antihypertensive drugs, nonsteroidal anti-inflam- dangers or threats. These responses are not subject to matory drugs (such as flurbiprofen and ibuprofen), and conscious control and are the same in humans as in local anesthetics. They represent an evolutionary adapta- symptoms when consumed in sufficient quantity.
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