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Currently there is no cure for myotubular or centronuclear myopathies. Treatment often focuses on trying to maximize functional abilities and minimize medical complications, and involvement by physicians specializing in Physical Medicine and Rehabilitation, and by physical therapists and occupational therapists.
Medical management generally involves efforts to prevent pulmonary complications, since lung infections can be fatal in patients lacking the muscle strength necessary to clear secretions via coughing. Medical devices to assist with coughing help patients maintain clear airways, avoiding mucous plugs and avoiding the need for tracheostomy tubes.
Monitoring for scoliosis is also important, since weakness of the trunk muscles can lead to deviations in spinal alignment, with resultant compromise of respiratory function. Many patients with congenital myopathies may eventually require surgical treatment of scoliosis.
In terms of the management of spinal and bulbar muscular atrophy, no cure is known and treatment is supportive. Rehabilitation to slow muscle weakness can prove positive, though the prognosis indicates some individuals will require the use of a wheelchair in later stages of life.
Surgery may achieve correction of the spine, and early surgical intervention should be done in cases where prolonged survival is expected. Preferred nonsurgical treatment occurs due to the high rate of repeated dislocation of the hip.
A 2006 study followed 223 patients for a number of years. Of these, 15 died, with a median age of 65 years. The authors tentatively concluded that this is in line with a previously reported estimate of a shortened life expectancy of 10-15 years (12 in their data).
Centronuclear myopathies (CNM) are a group of congenital myopathies where cell nuclei are abnormally located in skeletal muscle cells. In CNM the nuclei are located at a position in the center of the cell, instead of their normal location at the periphery.
Symptoms of CNM include severe hypotonia, hypoxia-requiring breathing assistance, and scaphocephaly. Among centronuclear myopathies, the X-linked myotubular myopathy form typically presents at birth, and is thus considered a congenital myopathy. However, some centronuclear myopathies may present later in life.
The treatment of primary immunodeficiencies depends foremost on the nature of the abnormality. Somatic treatment of primarily genetic defects is in its infancy. Most treatment is therefore passive and palliative, and falls into two modalities: managing infections and boosting the immune system.
Reduction of exposure to pathogens may be recommended, and in many situations prophylactic antibiotics or antivirals may be advised.
In the case of humoral immune deficiency, immunoglobulin replacement therapy in the form of intravenous immunoglobulin (IVIG) or subcutaneous immunoglobulin (SCIG) may be available.
In cases of autoimmune disorders, immunosuppression therapies like corticosteroids may be prescribed.
Bone marrow transplant may be possible for Severe Combined Immune Deficiency and other severe immunodeficiences.
Virus-specific T-Lymphocytes (VST) therapy is used for patients who have received hematopoietic stem cell transplantation that has proven to be unsuccessful. It is a treatment that has been effective in preventing and treating viral infections after HSCT. VST therapy uses active donor T-cells that are isolated from alloreactive T-cells which have proven immunity against one or more viruses. Such donor T-cells often cause acute graft-versus-host disease (GVHD), a subject of ongoing investigation. VSTs have been produced primarily by ex-vivo cultures and by the expansion of T-lymphocytes after stimulation with viral antigens. This is carried out by using donor-derived antigen-presenting cells. These new methods have reduced culture time to 10–12 days by using specific cytokines from adult donors or virus-naive cord blood. This treatment is far quicker and with a substantially higher success rate than the 3–6 months it takes to carry out HSCT on a patient diagnosed with a primary immunodeficiency. T-lymphocyte therapies are still in the experimental stage; few are even in clinical trials, none have been FDA approved, and availability in clinical practice may be years or even a decade or more away.
Brain MRI shows vermis atrophy or hypoplasic. Cerebral and cerebellar atrophy with white matter changes in some cases.
Galactosemic infants present clinical symptoms just days after the onset of a galactose diet. They include difficulty feeding, diarrhea, lethargy, hypotonia, jaundice, cataract, and hepatomegaly (enlarged liver). If not treated immediately, and many times even with treatment, severe mental retardation, verbal dyspraxia (difficulty), motor abnormalities, and reproductive complications may ensue. The most effective treatment for many of the initial symptoms is complete removal of galactose from the diet. Breast milk and cow's milk should be replaced with soy alternatives. Infant formula based on casein hydrolysates and dextrin maltose as a carbohydrate source can also be used for initial management, but are still high in galactose. The reason for long-term complications despite a discontinuation of the galactose diet is vaguely understood. However, it has been suggested that endogenous (internal) production of galactose may be the cause.
The treatment for galactosemic cataract is no different from general galactosemia treatment. In fact, galactosemic cataract is one of the few symptoms that is actually reversible. Infants should be immediately removed from a galactose diet when symptoms present, and the cataract should disappear and visibility should return to normal. Aldose reductase inhibitors, such as sorbinil, have also proven promising in preventing and reversing galactosemic cataracts. AR inhibitors hinder aldose reductase from synthesizing galactitol in the lens, and thus restricts the osmotic swelling of the lens fibers. Other AR inhibitors include the acetic acid compounds zopolrestat, tolrestat, alrestatin, and epalrestat. Many of these compounds have not been successful in clinical trials due to adverse pharmokinetic properties, inadequate efficacy and efficiency, and toxic side effects. Testing on such drug-treatments continues in order to determine potential long-term complications, and for a more detailed mechanism of how AR inhibitors prevent and reverse the galactosemic cataract.
X-linked myotubular myopathy (MTM) is a form of centronuclear myopathy (CNM) associated with myotubularin 1.
Genetically inherited traits and conditions are often referred to based upon whether they are located on the "sex chromosomes" (the X or Y chromosomes) versus whether they are located on "autosomal" chromosomes (chromosomes other than the X or Y). Thus, genetically inherited conditions are categorized as being sex-linked (e.g., X-linked) or autosomal. Females have two X-chromosomes, while males only have a single X chromosome, and a genetic abnormality located on the X chromosome is much more likely to cause clinical disease in a male (who lacks the possibility of having the normal gene present on any other chromosome) than in a female (who is able to compensate for the one abnormal X chromosome).
The X-linked form of MTM is the most commonly diagnosed type. Almost all cases of X-linked MTM occurs in males. Females can be "carriers" for an X-linked genetic abnormality, but usually they will not be clinically affected themselves. Two exceptions for a female with a X-linked recessive abnormality to have clinical symptoms: one is a manifesting carrier and the other is X-inactivation. A manifesting carrier usually has no noticeable problems at birth; symptoms show up later in life. In X-inactivation, the female (who would otherwise be a carrier, without any symptoms), actually presents with full-blown X-linked MTM. Thus, she congenitally presents (is born with) MTM.
Thus, although" MTM1" mutations most commonly cause problems in boys, these mutations can also cause clinical myopathy in girls, for the reasons noted above. Girls with myopathy and a muscle biopsy showing a centronuclear pattern should be tested for "MTM1" mutations.
Many clinicians and researchers use the abbreviations XL-MTM, XLMTM or X-MTM to emphasize that the genetic abnormality for myotubular myopathy (MTM) is X-linked (XL), having been identified as occurring on the X chromosome. The specific gene on the X chromosome is referred to as MTM-1. In theory, some cases of CNM may be caused by an abnormality on the X chromosome, but located at a different site from the gene "MTM1", but currently "MTM1" is the only X-linked genetic mutation site identified for myotubular or centronuclear myopathy. Clinical suspicion for X-linked inheritance would be a disease affecting multiple boys (but no girls) and a pedigree chart showing inheritance only through the maternal (mother’s) side of each generation.
Gillespie syndrome, also called aniridia, cerebellar ataxia and mental deficiency. is a rare genetic disorder. The disorder is characterized by partial aniridia (meaning that part of the iris is missing), ataxia (motor and coordination problems), and, in most cases, intellectual disability. It is heterogeneous, inherited in either an autosomal dominant or autosomal recessive manner. Gillespie syndrome was first described by American ophthalmologist Fredrick Gillespie in 1965.
Theoretically, a mutation in any of the may cause disease, but below are some notable ones, with short description of symptoms:
- Adrenoleukodystrophy; leads to progressive brain damage, failure of the adrenal glands and eventually death.
- Alport syndrome; glomerulonephritis, endstage kidney disease, and hearing loss.
- Androgen insensitivity syndrome; variable degrees of undervirilization and/or infertility in XY persons of either gender
- Barth syndrome; metabolism distortion, delayed motor skills, stamina deficiency, hypotonia, chronic fatigue, delayed growth, cardiomyopathy, and compromised immune system.
- Blue cone monochromacy; low vision acuity, color blindness, photophobia, infantile nystagmus.
- Centronuclear myopathy; where cell nuclei are abnormally located in skeletal muscle cells. In CNM the nuclei are located at a position in the center of the cell, instead of their normal location at the periphery.
- Charcot–Marie–Tooth disease (CMTX2-3); disorder of nerves (neuropathy) that is characterized by loss of muscle tissue and touch sensation, predominantly in the feet and legs but also in the hands and arms in the advanced stages of disease.
- Coffin–Lowry syndrome; severe mental retardation sometimes associated with abnormalities of growth, cardiac abnormalities, kyphoscoliosis as well as auditory and visual abnormalities.
- Fabry disease; A lysosomal storage disease causing anhidrosis, fatigue, angiokeratomas, burning extremity pain and ocular involvement.
- Hunter's Syndrome; potentially causing hearing loss, thickening of the heart valves leading to a decline in cardiac function, obstructive airway disease, sleep apnea, and enlargement of the liver and spleen.
- Hypohidrotic ectodermal dysplasia, presenting with hypohidrosis, hypotrichosis, hypodontia
- Kabuki syndrome; multiple congenital anomalies and mental retardation.
- Spinal and bulbar muscular atrophy; muscle cramps and progressive weakness
- Lesch-Nyhan syndrome; neurologic dysfunction, cognitive and behavioral disturbances including self-mutilation, and uric acid overproduction (hyperuricemia)
- Lowe Syndrome; hydrophthalmia, cataracts, intellectual disabilities, aminoaciduria, reduced renal ammonia production and vitamin D-resistant rickets
- Menkes disease; sparse and coarse hair, growth failure, and deterioration of the nervous system
- Nasodigitoacoustic syndrome; mishaped nose, brachydactyly of the distal phalanges, sensorineural deafness
- Nonsyndromic deafness; hearing loss
- Norrie disease; cataracts, leukocoria along with other developmental issues in the eye
- Occipital horn syndrome; deformations in the skeleton
- Ocular albinism; lack of pigmentation in the eye
- Ornithine transcarbamylase deficiency; developmental delay and mental retardation. Progressive liver damage, skin lesions, and brittle hair may also be seen
- Siderius X-linked mental retardation syndrome; cleft lip and palate with mental retardation and facial dysmorphism, caused by mutations in the histone demethylase PHF8
- Simpson-Golabi-Behmel syndrome; coarse faces with protruding jaw and tongue, widened nasal bridge, and upturned nasal tip
- Spinal muscular atrophy caused by UBE1 gene mutation; weakness due to loss of the motor neurons of the spinal cord and brainstem
- Wiskott-Aldrich syndrome; eczema, thrombocytopenia, immune deficiency, and bloody diarrhea
- X-linked Severe Combined Immunodeficiency (SCID); infections, usually causing death in the first years of life
- X-linked sideroblastic anemia; skin paleness, fatigue, dizziness and enlarged spleen and liver.
The most common X-linked recessive disorders are:
- Red-green color blindness, a very common trait in humans and frequently used to explain X-linked disorders. Between seven and ten percent of men and 0.49% to 1% of women are affected. Its commonness may be explained by its relatively benign nature. It is also known as daltonism.
- Hemophilia A, a blood clotting disorder caused by a mutation of the Factor VIII gene and leading to a deficiency of Factor VIII. It was once thought to be the "royal disease" found in the descendants of Queen Victoria. This is now known to have been Hemophilia B (see below).
- Hemophilia B, also known as Christmas Disease, a blood clotting disorder caused by a mutation of the Factor IX gene and leading to a deficiency of Factor IX. It is rarer than hemophilia A. As noted above, it was common among the descendants of Queen Victoria.
- Duchenne muscular dystrophy, which is associated with mutations in the dystrophin gene. It is characterized by rapid progression of muscle degeneration, eventually leading to loss of skeletal muscle control, respiratory failure, and death.
- Becker's muscular dystrophy, a milder form of Duchenne, which causes slowly progressive muscle weakness of the legs and pelvis.
- X-linked ichthyosis, a form of ichthyosis caused by a hereditary deficiency of the steroid sulfatase (STS) enzyme. It is fairly rare, affecting one in 2,000 to one in 6,000 males.
- X-linked agammaglobulinemia (XLA), which affects the body's ability to fight infection. XLA patients do not generate mature B cells. B cells are part of the immune system and normally manufacture antibodies (also called immunoglobulins) which defends the body from infections (the humoral response). Patients with untreated XLA are prone to develop serious and even fatal infections.
- Glucose-6-phosphate dehydrogenase deficiency, which causes nonimmune hemolytic anemia in response to a number of causes, most commonly infection or exposure to certain medications, chemicals, or foods. Commonly known as "favism", as it can be triggered by chemicals existing naturally in broad (or fava) beans.
Due to its mild presentation, MAIS often goes unnoticed and untreated. Management of MAIS is currently limited to symptomatic management; methods to correct a malfunctioning androgen receptor protein that result from an AR gene mutation are not currently available. Treatment includes surgical correction of mild gynecomastia, minor hypospadias repair, and testosterone supplementation. Supraphysiological doses of testosterone have been shown to correct diminished secondary sexual characteristics in men with MAIS, as well as to reverse infertility due to low sperm count. As is the case with PAIS, men with MAIS will experience side effects from androgen therapy (such as the suppression of the hypothalamic-pituitary-gonadal axis) at a higher dosage than unaffected men. Careful monitoring is required to ensure the safety and efficacy of treatment. Regular breast and prostate examinations may be necessary due to comorbid association with breast and prostate cancers.
Medications to treat CPVT include beta blockers and verapamil.
Flecainide inhibits the release of the cardiac ryanodine receptor–mediated Ca, and is therefore believed to medicate the underlying molecular cause of CPVT in both mice and humans.
Tamoxifen, a selective estrogen receptor modulator (SERM) with antiestrogenic actions in breast tissue and estrogenic actions in bone, has been found to be highly effective in preventing and reversing bicalutamide-induced gynecomastia in men. Moreover, in contrast to analogues (which also alleviate bicalutamide-induced gynecomastia), tamoxifen poses minimal risk of accelerated bone loss and osteoporosis. For reasons that are unclear, anastrozole, an aromatase inhibitor (or an inhibitor of estrogen biosynthesis), has been found to be much less effective in comparison to tamoxifen for treating bicalutamide-induced gynecomastia. A systematic review of -induced gynecomastia and breast tenderness concluded that tamoxifen (10–20 mg/day) and radiotherapy could effectively manage the side effect without relevant adverse effects, though with tamoxifen showing superior effectiveness. Surgical breast reduction may also be employed to correct bicalutamide-induced gynecomastia.
In recent reports, left cardiac sympathetic denervation and bilateral thoracoscopic sympathectomy have shown promising results in individuals whose symptoms cannot be controlled by beta blockers.
Although advancement has been slow to come during the decades of research dedicated to the galactosemic cataract, some notable additions have been made. In 2006, Michael L. Mulhern and colleagues further investigated the effects of the osmotic swelling on galactosemic cataract development. Experiments were based on systematic observation of rats fed a 50% galactose diet. According to Mulhern, 7 to 9 days after the onset of the galactose diet, lenses appeared hydrated and highly vacuolated. Lens fibers became liquefied after nine days of the diet, and nuclear cataract formation appeared after 15 days of the diet.
The experiment concluded that
Apoptosis in lens epithelial cells (LEC) is linked to cataract formation. Essentially, the study suggested that the mechanism outlined by Friedenwald and Kinoshita, which centers on osmotic swelling of the lens fibers, is just the beginning in a cascade of events that causes and progresses the galactosemic cataract. Mulhern determined that osmotic swelling is actually a cataractogenic stressor that leads to LEC apoptosis. This is because osmotic swelling of lens fibers considerably strains LEC endoplasmic reticula. As the endoplasmic reticulum is the principal site of protein synthesis, stressors on the ER can cause proteins to become misfolded. The subsequent accumulation of misfolded proteins in the ER activates the unfolded protein response (UPR) in LECs. In agreement, it was later observed on galactosemic yeast models, the activation of UPR upon galactose treatment. UPR initiates apoptosis, or cell death, by various mechanisms, one of which is the release of reactive oxygen species (ROS). Thus, according to recent findings, osmotic swelling, UPR, oxidative damage, and the resultant LEC apoptosis all play key roles in the onset and progression of the galactosemic cataract. Other studies claim that the oxidative damage in LECs is less a result of the release of ROS and more because of the competition between aldose reductase and glutathione reductase for nicotinamide adenine dinucleotide phosphate (NADPH). Aldose reductase requires NADPH for the reduction of galactose to galactitol, while glutathione reductase utilizes NADPH to reduce glutathione disulfide (GSSG) to its sulfhydryl form, GSH. GSH is an important cellular antioxidant. Therefore, what exactly the key roles are for these cataractogenic factors is not yet fully understood or agreed upon by researchers.
The most common side effects of bicalutamide monotherapy in men are breast pain/tenderness and gynecomastia. These side effects may occur in as many as 90% of men treated with bicalutamide monotherapy, but gynecomastia is generally reported to occur in 70 to 80% of patients. In the trial, at a median follow-up of 7.4 years, breast pain and gynecomastia respectively occurred in 73.6% and 68.8% of men treated with 150 mg/day bicalutamide monotherapy. In more than 90% of affected men, bicalutamide-related breast events are mild-to-moderate in severity. It is only rarely and in severe and extreme cases of gynecomastia that the proportions of the male breasts become so marked that they are comparable to those of women. In the trial, 16.8% of bicalutamide patients relative to 0.7% of controls withdrew from the study due to breast pain and/or gynecomastia. The incidence and severity of gynecomastia are higher with estrogens (e.g., diethylstilbestrol) than with like bicalutamide in the treatment of men with prostate cancer.
Most cases of vaginal hypoplasia associated with CAIS can be corrected using non-surgical pressure methods. The elastic nature of vaginal tissue, as demonstrated by its ability to accommodate the differences in size between a tampon, a penis, and a baby's head, make dilation possible even in cases when the vaginal depth is significantly compromised. Treatment compliance is thought to be critical to achieve satisfactory results. Dilation can also be achieved via the Vecchietti procedure, which stretches vaginal tissues into a functional vagina using a traction device that is anchored to the abdominal wall, subperitoneal sutures, and a mold that is placed against the vaginal dimple. Vaginal stretching occurs by increasing the tension on the sutures, which is performed daily. The non-operative pressure dilation method is currently recommended as the first choice, since it is non-invasive, and highly successful. Vaginal dilation should not be performed before puberty.
Some have hypothesized that supraphysiological levels of estrogen may reduce the diminished bone mineral density associated with CAIS. Data has been published that suggests affected women who were not compliant with estrogen replacement therapy, or who had a lapse in estrogen replacement, experienced a more significant loss of bone mineral density. Progestin replacement therapy is seldom initiated, due to the absence of a uterus. Androgen replacement has been reported to increase a sense of well-being in gonadectomized women with CAIS, although the mechanism by which this benefit is achieved is not well understood.
There are three treatment options available to a patient. These options are observation, microsurgical removal and radiation (radiosurgery or radiotherapy). Determining which treatment to choose involves consideration of many factors including the size of the tumor, its location, the patient's age, physical health and current symptoms. About 25% of all acoustic neuromas are treated with medical management consisting of a periodic monitoring of the patient's neurological status, serial imaging studies, and the use of hearing aids when appropriate.
One of the last great obstacles in the management of acoustic neuromas is hearing preservation and/or rehabilitation after hearing loss. Hearing loss is both a symptom and concommitant risk, regardless of the treatment option chosen.
Treatment does not restore hearing already lost, though there are a few rare cases of hearing recovery reported.
A diagnosis of NF2 related bilateral acoustic neuromas creates the possibility of complete deafness if the tumors are left to grow unchecked. Preventing or treating the complete deafness that may befall individuals with NF2 requires complex decision making. The trend at most academic U.S. medical centers is to recommend treatment for the smallest tumor which has the best chance of preserving hearing. If this goal is successful, then treatment can also be offered for the remaining tumor. If hearing is not preserved at the initial treatment, then usually the second tumor, in the only-hearing ear, is just observed. If it shows continued growth and becomes life-threatening, or if the hearing is lost over time as the tumor grows, then treatment is undertaken. This strategy has the highest chance of preserving hearing for the longest time possible.
Testosterone has been used to successfully treat undervirilization in some but not all men with PAIS, despite having supraphysiological levels of testosterone to start with. Treatment options include transdermal gels or patches, oral or injectable testosterone undecanoate, other injectable testosterone esters, testosterone pellets, or buccal testosterone systems. Supraphysiological doses may be required to achieve the desired physiological effect, which may be difficult to achieve using non-injectable testosterone preparations. Exogenous testosterone supplementation in unaffected men can produce various unwanted side effects, including prostatic hypertrophy, polycythemia, gynecomastia, hair loss, acne, and the suppression of the hypothalamic-pituitary-gonadal axis, resulting in the reduction of gonadotropins (i.e., luteinizing hormone and follicle-stimulating hormone) and spermatogenic defect. These effects may not manifest at all in men with AIS, or might only manifest at a much higher concentration of testosterone, depending on the degree of androgen insensitivity. Those undergoing high dose androgen therapy should be monitored for safety and efficacy of treatment, possibly including regular breast and prostate examinations. Some individuals with PAIS have a sufficiently high sperm count to father children; at least one case report has been published that describes fertile men who fit the criteria for grade 2 PAIS (micropenis, penile hypospadias, and gynecomastia). Several publications have indicated that testosterone treatment can correct low sperm counts in men with MAIS. At least one case report has been published that documents the efficacy of treating a low sperm-count with tamoxifen in an individual with PAIS.
Management of AIS is currently limited to symptomatic management; no method is currently available to correct the malfunctioning androgen receptor proteins produced by "AR" gene mutations. Areas of management include sex assignment, genitoplasty, gonadectomy in relation to tumor risk, hormone replacement therapy, genetic counseling, and psychological counseling.
Management of AIS is currently limited to symptomatic management; methods to correct a malfunctioning androgen receptor protein that result from an AR gene mutation are not currently available. Areas of management include sex assignment, genitoplasty, gonadectomy in relation to tumor risk, hormone replacement therapy, and genetic and psychological counseling.
Since acoustic neuromas tend to be slow-growing and are benign tumors, careful observation over a period of time may be appropriate for some patients. When a small tumor is discovered in an older patient, observation to determine the growth rate of the tumor may be indicated if serious symptoms are not present. There is now good evidence from large observational studies that suggest many small tumors in older individuals do not grow, thus allowing tumors with no growth to be observed successfully. If the tumor grows, treatment may become necessary.
Another example of a group of patients for whom observation may be indicated includes patients with a tumor in their only hearing or better hearing ear, particularly when the tumor is of a size that hearing preservation with treatment would be unlikely. In this group of patients, MRI is used to follow the growth pattern. Treatment is recommended if either the hearing is lost or the tumor size becomes life-threatening, thus allowing the patient to retain hearing for as long as possible.
Current studies suggest surgeons should observe small acoustic neuromas (those 1.5 cm or less).
Over a period of 10 years of observation with no treatment, 45% of patients with small tumors (and therefore minimal symptoms) lose functional hearing on the affected side; this percentage is considerably higher than that for patients actively treated with hearing-preserving microsurgery or radiosurgery.