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While choroideremia is an ideal candidate for gene therapy there are other potential therapies that could restore vision after it has been lost later in life. Foremost of these is stem cell therapy. A clinical trial published in 2014 found that a subretinal injection of human embryonic stem cells in patients with age-related macular degeneration and Stargardt disease was safe and improved vision in most patients. Out of 18 patients, vision improved in 10, improved or remained the same in 7, and decreased in 1 patient, while no improvement was seen in the untreated eyes. The study found "no evidence of adverse proliferation, rejection, or serious ocular or systemic safety issues related to the transplanted tissue." A 2015 study used CRISPR/Cas9 to repair mutations in patient-derived induced pluripotent stem cells that cause X-linked retinitis pigmentosa. This study suggests that a patient's own repaired cells could be used for therapy, reducing the risk of immune rejection and ethical issues that come with the use of embryonic stem cells.
Gene therapy is currently not a treatment option, however human clinical trials for both choroideremia and Leber's congenital amaurosis (LCA) have produced somewhat promising results.
Clinical trials of gene therapy for patients with LCA began in 2008 at three different sites. In general, these studies found the therapy to be safe, somewhat effective, and promising as a future treatment for similar retinal diseases.
In 2011, the first gene therapy treatment for choroideremia was administered. The surgery was performed by Robert MacLaren, Professor of Ophthalmology at the University of Oxford and leader of the Clinical Ophthalmology Research Group at the Nuffield Laboratory of Ophthalmology (NLO).
In the study, 2 doses of the AAV.REP1 vector were injected subretinally in 12 patients with choroideremia.
There study had 2 objectives:
- to assess the safety and tolerability of the AAV.REP1 vector
- to observe the therapeutic benefit, or slowing of the retinal degeneration, of the gene therapy during the study and at a 24-month post-treatment time point
Despite retinal detachment caused by the injection, the study observed initial improved rod and cone function, warranting further study.
In 2016, researchers were optimistic that the positive results of 32 choroideremia patients treated over four and a half years with gene therapy in four countries could be long-lasting.
Fukuyama congenital muscular dystrophy has a poor prognosis. Most children with FCMD reach a maximum mobility at sitting upright and sliding. Due to the compounded effects of continually worsening heart problems, impaired mental development, problems swallowing and additional complications, children with FCMD rarely live through adolescence, the disorder proves fatal by age 20.
Reis-Bücklers corneal dystrophy is not associated with any systemic conditions.
Though there is no treatment for Cone dystrophy, certain supplements may help in delaying the progression of the disease.
The beta-carotenoids, lutein and zeaxanthin, have been evidenced to reduce the risk of developing age related macular degeneration (AMD), and may therefore provide similar benefits to Cone dystrophy sufferers.
Consuming omega-3 fatty acids (docosahexaenoic acid and eicosapentaenoic acid) has been correlated with a reduced progression of early AMD, and in conjunction with low glycemic index foods, with reduced progression of advanced AMD, and may therefore delay the progression of cone dystrophy.
It was described by Chuta Oguchi (1875-1945), a Japanese ophthalmologist, in 1907. The characteristic fundal appearances were described by Mizuo in 1913.
Treatment of the disease is limited. In the People's Republic of China, high doses of Vitamin K and zinc are infused but thus treatment has been declared as quackery in the Republic of China (Taiwan) and by the Timor Leste Academy of Ophthalmology. In the U.S., afflicted persons have taken high doses of zinc (240 mg every two hours).
There is no cure for retinitis pigmentosa, but the efficacy and safety of various prospective treatments are currently being evaluated. The efficiency of various supplements, such as Vitamin A, DHA, and Lutein, in delaying disease progression remains an unresolved, yet prospective treatment option. Clinical trials investigating optic prosthetic devices, gene therapy mechanisms, and retinal sheet transplantations are active areas of study in the partial restoration of vision in retinitis pigmentosa patients.
Studies have demonstrated the delay of rod photoreceptor degeneration by the daily intake of 15000 IU (equivalent to 4.5 mg) of vitamin A palmitate; thus, stalling disease progression in some patients. Recent investigations have shown that proper vitamin A supplementation can postpone blindness by up to 10 years (by reducing the 10% loss pa to 8.3% pa) in some patients in certain stages of the disease.
The Argus retinal prosthesis became the first approved treatment for the disease in February 2011, and is currently available in Germany, France, Italy, and the UK. Interim results on 30 patients long term trials were published in 2012. The Argus II retinal implant has also received market approval in the US. The device may help adults with RP who have lost the ability to perceive shapes and movement to be more mobile and to perform day-to-day activities. In June 2013, twelve hospitals in the US announced they would soon accept consultation for patients with RP in preparation for the launch of Argus II later that year. The Alpha-IMS is a subretinal implant involving the surgical implantation of a small image-recording chip beneath the optic fovea. Measures of visual improvements from Alpha-IMS studies require the demonstration of the device's safety before proceeding with clinical trials and granting market approval.
The goal of gene therapy studies is to virally supplement retinal cells expressing mutant genes associated with the retinitis pigmentosa phenotype with healthy forms of the gene; thus, allowing the repair and proper functioning of retinal photoreceptor cells in response to the instructions associated with the inserted healthy gene. Clinical trials investigating the insertion of the healthy RPE65 gene in retinas expressing the LCA2 retinitis pigmentosa phenotype measured modest improvements in vision; however, the degradation of retinal photoreceptors continued at the disease-related rate. Likely, gene therapy may preserve remaining healthy retinal cells while failing to repair the earlier accumulation of damage in already diseased photoreceptor cells. Response to gene therapy would theoretically benefit young patients exhibiting the shortest progression of photoreceptor decline; thus, correlating to a higher possibility of cell rescue via the healthy inserted gene.
The prognosis of this sub-type of MD indicates that the affected individual may eventually have feeding difficulties. Surgery, at some point, might be an option for scoliosis.
Scoliosis which is a sideways curve of the persons vertebrate, is determined by a variety of factors, including the degree (mild or severe), in which case if possible a brace might be used by the individual
Currently this sub-type of muscular dystrophy has no cure and no "definitive" treatment exists. Treatment offers preventative tactics to delay muscle breakdown and increase life expectancy. Stretching and physical therapy can increase mobility. Treatment also includes correcting skeletal abnormalities through orthopedic surgery and other orthopedic techniques. Antiepileptic medication is administered to help prevent seizures. ACE inhibitors and beta blockers help treat heart conditions, and respiratory assistance is more than likely needed at some point for the affected individual
In terms of possible research for Ullrich congenital muscular dystrophy one source indicates that cyclosporine A might be of benefit to individuals with this CMD type.
According to a review by Bernardi, et al., cyclosporin A (CsA) used to treat collagen VI muscular dystrophies demonstrates a normalization of mitochondrial reaction to rotenone.
Congenital stromal corneal dystrophy (CSCD), also called Witschel dystrophy, is an extremely rare, autosomal dominant form of corneal dystrophy. Only 4 families have been reported to have the disease by 2009. The main features of the disease are numerous opaque flaky or feathery areas of clouding in the stroma that multiply with age and eventually preclude visibility of the endothelium. Strabismus or primary open angle glaucoma was noted in some of the patients. Thickness of the cornea stays the same, Descemet's membrane and endothelium are relatively unaffected, but the fibrills of collagen that constitute stromal lamellae are reduced in diameter and lamellae themselves are packed significantly more tightly.
Currently no cure or specific treatment exists to eliminate the symptoms or stop the disease progression. A consistent diet planned with the help of a dietitian along with exercises taught by a speech therapist can assist with mild symptoms of dysphagia. Surgical intervention can also help temporarily manage symptoms related to the ptosis and dysphagia. Cutting one of the throat muscles internally, an operation called cricopharyngeal myotomy, can be one way to ease symptoms in more severe cases.
Physical therapy and specifically designed exercises may assist with proximal limb weakness, though there is still no current definitive data showing it will stop the progress of the disease. Many of those affected with the proximal limb weakness will eventually require assistive devices such as a wheelchair. As with all surgical procedures, they come with many risk factors. As the dysphagia becomes more severe, patients become malnourished, lose significant weight, become dehydrated and suffer from repeated incidents of aspiration pneumonia. These last two are often the cause of death.
Treatment is aimed at managing the symptoms of the disease. A form of laser eye surgery named keratectomy may help with the superficial corneal scarring. In more severe cases, a partial or complete corneal transplantation may be considered. However, it is common for the dystrophy to recur within the grafted tissue.
Duchenne muscular dystrophy is a rare progressive disease which eventually affects all voluntary muscles and involves the heart and breathing muscles in later stages. As of 2013, the life expectancy is estimated to be around 25, but this varies. With excellent medical care males are often living into their 30s.
In rare cases, people with DMD have been seen to survive into their forties or early fifties, with proper positioning in wheelchairs and beds, and the use of ventilator support (via tracheostomy or mouthpiece), airway clearance, and heart medications. Early planning of the required supports for later-life care has shown greater longevity for people with DMD.
Curiously, in the mdx mouse model of Duchenne muscular dystrophy, the lack of dystrophin is associated with increased calcium levels and skeletal muscle myonecrosis. The intrinsic laryngeal muscles (ILMs) are protected and do not undergo myonecrosis. ILMs have a calcium regulation system profile suggestive of a better ability to handle calcium changes in comparison to other muscles, and this may provide a mechanistic insight for their unique pathophysiological properties. The ILM may facilitate the development of novel strategies for the prevention and treatment of muscle wasting in a variety of clinical scenarios.
There is no known cure for Becker muscular dystrophy yet. Treatment is aimed at control of symptoms to maximize the quality of life which can be measured by specific questionnaires. Activity is encouraged. Inactivity (such as bed rest) or sitting down for too long can worsen the muscle disease. Physical therapy may be helpful to maintain muscle strength. Orthopedic appliances such as braces and wheelchairs may improve mobility and self-care.
Immunosuppressant steroids have been known to help slow the progression of Becker muscular dystrophy. The drug prednisone contributes to an increased production of the protein utrophin which closely resembles dystrophin, the protein that is defective in BMD.
The cardiac problems that occur with EDMD and myotonic muscular dystrophy may require a pacemaker.
The investigational drug Debio-025 is a known inhibitor of the protein cyclophilin D, which regulates the swelling of mitochondria in response to cellular injury. Researchers decided to test the drug in mice engineered to carry MD after earlier laboratory tests showed deleting a gene that encodes cycolphilin D reduced swelling and reversed or prevented the disease’s muscle-damaging characteristics. According to a review by Bushby, et al. if a primary protein is not functioning properly then maybe another protein could take its place by augmenting it. Upregulation of compensatory proteins has been done in models of transgenic mice.
Several mutations have been implicated as a cause of Oguchi disease. These include mutations in the arrestin gene or the rhodopsin kinase gene.
The condition is more frequent in individuals of Japanese ethnicity.
There is a variety of research under way targeted at various forms of limb-girdle muscular dystrophy. Among the methods thought to hold promise for treatment include gene transfer therapy, which works by inserting in cells of defective genes with a healthy gene.
According to a review by Bengtsson et al. some success with AAV-mediated gene therapies (for different disorders) have increased interest in researchers, with CRISPR/Cas9 and exon-skipping helping these therapeutic goals along. Limb-girdle muscular dystrophies has many different types which are due to different gene mutations. LGMD2D is caused by a mutation in the α-sarcoglycan gene.Future treatment could be had by gene therapy through recombinant adeno-associated vectors.
Conversely, according to a review by Straub, et al. there are several research issues that need to be targeted, the rareness of the disease, our poor understanding of the mechanism of LGMD2, and absence of patient cohorts, consequently biomarkers for individuals with LGMD2 are lacking. The review goes on to state that animal models for LGMD2 have been used to analyse therapeutic medications. Also adding that while prednisone has been used and has had positive effects on affected LGMD2 individuals there is still no evidence of its effectiveness in trials that are placebo-controlled
It was concluded by Mousa-Al et al. that the disease is different from a disease known as spastic ataxia-corneal dystrophy syndrome that had been found a year later in 1986 in an inbred Bedouin family. Corneal-cerebellar syndrome differs from the spastic ataxia-corneal dystrophy syndrome by causing mental retardation. Corneal dystrophy is also epithelian instead of being stromal.
Future treatments may involve retinal transplants, artificial retinal implants, gene therapy, stem cells, nutritional supplements, and/or drug therapies.
2006: UK researchers transplanted mouse stem cells which were at an advanced stage of development, and already programmed to develop into photoreceptor cells, into mice that had been genetically induced to mimic the human conditions of retinitis pigmentosa and age-related macular degeneration. These photoreceptors developed and made the necessary neural connections to the animal's retinal nerve cells, a key step in the restoration of sight. Previously it was believed that the mature retina has no regenerative ability. This research may in the future lead to using transplants in humans to relieve blindness.
2008: Scientists at the Osaka Bioscience Institute have identified a protein, named Pikachurin, which they believe could lead to a treatment for retinitis pigmentosa.
2008: Retinitis pigmentosa was attempted to be linked to gene expression of FAM46A.
2010: A possible gene therapy seems to work in mice.
2012: Scientists at the Columbia University Medical Center showed on an animal model that gene therapy and induced pluripotent stem cell therapy may be viable options for treating retinitis pigmentosa in the future.
2012: Scientists at the University of Miami Bascom Palmer Eye Institute presented data showing protection of photoreceptors in an animal model when eyes were injected with mesencephalic astrocyte-derived neurotrophic factor (MANF).
Researchers at the University of California, Berkeley were able to restore vision to blind mice by exploiting a "photoswitch" that activates retinal ganglion cells in animals with damaged rod and cone cells.
2015: A study by Bakondi et al. at Cedars-Sinai Medical Center showed that CRISPR/Cas9 can be used to treat rats with the autosomal dominant form of retinitis pigmentosa.
2016: RetroSense Therapeutics aimed to inject viruses with DNA from light-sensitive algae into the eyes of several blind people (who have retinitis pigmentosa). If successful, they will be able to see in black and white.
Corneal transplant is not needed except in very severe and late cases.
Light sensitivity may be overcome by wearing tinted glassess.
Corneal-cerebellar syndrome (also known as Der Kaloustian-Jarudi-Khoury syndrome) is an autosomally resessive disease that was first described in 1985. Three cases are known: all are sisters in the same family.
Thiel–Behnke dystrophy, or Corneal dystrophy of Bowman layer, type II, is a rare form of corneal dystrophy affecting the layer that supports corneal epithelium.
The dystrophy was first described in 1967 and initially suspected to denote the same entity as the earlier-described Reis-Bucklers dystrophy, but following a study in 1995 by Kuchle et al. the two look-alike dystrophies were deemed separate disorders.
Jalili syndrome is a genetic disorder characterized by the combination of cone-rod dystrophy of the retina and amelogenesis imperfecta. It was characterized in 1988 by Dr. I. K. Jalili and Dr. N. J. D. Smith, following the examination of 29 members of an inbred, Arab family living within the Gaza Strip.
Some cases of it are linked to chromosome 10q24, others stem from a mutation in the TGFBI gene.
Macular corneal dystrophy, also known as Fehr corneal dystrophy named for German ophthalmologist Oskar Fehr (1871-1959), is a rare pathological condition affecting the stroma of cornea. The first signs are usually noticed in the first decade of life, and progress afterwards, with opacities developing in the cornea and attacks of pain. The condition was first described by Arthur Groenouw in 1890.