Inherited Retinal Dystrophies (IRD)

Usher syndrome is a genetic disorder that causes its victims to get retnis pigmentosa (RP), or a disease that affects someone’s retinas resulting in tunnel vision, and hearing loss. The most common gene that becomes mutated is gene USH2A, this is a protein producing gene. It is a mutated recessive gene, meaning that in order to inherit Usher syndrome both parents have to be carriers of it. Once the child gets Usher syndrome, they will experience loss of eyesight and hearing.

Genetic screening is done with RFLP analysis. RFLP stands for Restriction Fragment Length Polymorphism. RFLP analysis is used to find an identifiable pattern of fragments (an RFLP) that indicates a genetic marker. The genetic marker is unique and is inherited in all people with a disorder or disease. The RFLP comes from a strand of DNA near a suspected gene location that has been cut with a restriction enzyme into smaller pieces. The pieces of DNA are separated using gel electrophoresis into their distinctive bands. The RFLP is a distinctive pattern of the fragments in the gel. All people with the disorder or disease have the RFLP pattern, it is written in stone or in this case, DNA. DNA bands are studied to determine if a person has a disease, is a carrier, has no prior deposition to the disease, or if they will develop the disease in the future. A detailed human map is being developed by scientists worldwide who are contributing information to the human genome project. The human genome project is an attempt to map out every gene on every chromosome of the human genome. It is going slowly, but growth in knowledge of the genome is growing exponentially every year. Along with the growth, we are accumulating knowledge about more

Macular Degeneration is a disease of the eye that gradually causes loss of a person’s central vision. Approximately 1.75 million Americans suffer from vision loss associated with the disease (All About Vision 1). The leading cause of blindness in people over the age of 60, Macular Degeneration, exists in two types (National Eye Institute 1). Both the wet and dry versions of the disease have similarities in risk factors, but differ in symptoms and treatments.

Retinitis pigmentosa is a group of inheritable diseases that is characterized by gradual deterioration of the photoreceptors in the retina. The photoreceptor cells in the retina, rod cells, are light sensitive cells that are able to sense low levels of light. The frequency of retinitis pigmentosa is one in four thousand births (Deng et al., 2015; Fahim et al., 2012; Haddad et al., 2016; Shu et al., 2012) People affected by retinitis pigmentosa will typically exhibit symptoms of night-blindness first, and this will precede a loss in the patient’s visual acuity field that starts from the outer edge and gradually moves inward resulting in a much smaller visual field and loss of peripheral vision, also known as tunnel vision (Haddad et al., 2016).

To understand the diverse causes of RP, a basic understanding of visual perception is required. Phototransduction (conversion of light to electrical signals) occurs first, which is initiated by two types of photoreceptors: rods and cones. These two types vary in their function as rods are primarily responsible for night vision and lack sensitivity to color while cones function in color vision. Light contacts these photoreceptors, and isomerizes a retinaldehydechromophore (retinal) which is bound to varying types of opsin proteins corresponding in their reactivity to different wavelengths of light. Upon absorption of a photon of light, the chromophore 11-cis-retinal is isomerized to the all-trans confirmation, which subsequently causes a series of molecular interactions which ultimately result in the electrical response of the photoreceptors (Vugler 2010). As 11-cis-retinal is required to absorb photons of light, this compound must be regenerated, a function that is performed with the aid of nearby cells of the retinal pigment epithelium

hereditary disorder of Caucasians in the United States and is the most common cause of chronic

Muscular dystrophy (MD) is a genetic disorder caused by incorrect or missing genetic information that leads to the gradual weakening of the muscle cells. Various causes lead to weak and deteriorating muscles depending on the type of muscular dystrophy the patient was affected by. However, there are many causes for muscular dystrophy due to the fact that there are thirty forms of muscular dystrophy, which are categorized under several categories. All are ultimately caused by autosomal recessive, autosomal dominant, sex-linked, and random mutations in very rare cases.

Age-related macular degeneration also known as AMD is a disease leading to severe vision and legal blindness in the elderly population. I will address the health condition description and the disability and functional implications who suffer from this disease.

The reading shows disease and inheritance in an entirely new light. It introduces the idea that genetically inherited diseases may have been selected for, which means that they must provide certain evolutionary advantages. It reorients the reader’s perspective about a disease like hemochromatosis, which has the potential to be incredibly harmful and even deadly, establishing that it may have once provided protection from the bubonic plague, making it an advantageous trait. This brings other genetic diseases into question, examining why diseases that appear to be harmful have not been eliminated from the gene pool. The idea that a disease that is harmful and dangerous in modern times could have once been a beneficial adaptation is very interesting.

The development of the human body is an exquisite process that involves numerous complicated processes for even the smallest of body parts, including the eyes. The eyes are an extraordinarily complex organ capable of gathering information through refracted light and sending it the brain to assemble a picture. They provide the ability to see and follow a moving object and the capability to tell an approximate distance of an object. When light passes through the cornea and iris pupil, at the anterior portion of the eye, it is focused by the lens onto the retina at the back of the eye. Photoreceptor cells, which are present in the retina, detect the light and send information to interneurons which begin to sort out the information. This information is then sent to ganglion cells which transmits the final information to the brain (Sowden 199). Because the eyes have such complicated and exquisite processes, the likelihood of developmental errors occurring are possible. A large number of these developmental errors lead to congenital defects and abnormalities that effect the individual’s eye sight. Some of these defects and abnormalities can cause serious diseases and syndromes that effect more than just the eyes, but also neurological processes, facial dimorphisms, growth failure, tracheal development, and genitalia anomalies.

screenings in multiple populations, it was concluded that the most common mutation shared between Caucasians is R864X.

This paper considers that focused primarily on human iris. This choice of this topic was made due to interest of wanting to provide knowledge about the factors that determine eye color. I know, like hair or skin, brown eyes are dominant over blue eye genes. I also know that a person can be identified by the retina scanners because everyone has their iris with unique structural patterns.

     Basically what my research is stating is that there is a major genetic component that contributes to this disease. There are three general types of hereditary Macular Degeneration. The first is called early onset. This is when you get it when you are four years of age up to seven. In this type both parents and their children can be affected. This means it is dominantly inherited. Most of the time this is called Best Disease or Viteliform Macular Degeneration.

Three other genes make proteins that are also involved in melanin pigment formation and albinism, but the exact role of these proteins remains unknown. These genes are the P gene on chromosome 15, the Hermansky--Pudlak syndrome gene on chromosome 10, and the ocular albinism gene on the X chromosome.

Prematurity is the main risk factor for RDS. Other risk factors associated with RDS include maternal diabetes, multiple gestation, elective cesarean delivery without labor, Caucasian race, male sex, precipitous delivery, and perinatal asphyxia. Factors associated with decreased risk for RDS include chronic hypertension, pre-eclampsia, chorioamnionitis, and prolonged rupture of membranes.