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Ocular Albinism
Ocular albinism is a form of albinism which, in contrast to oculocutaneous albinism, presents primarily in the eyes. There are multiple forms of ocular albinism, which are clinically similar.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. . Both known genes are on the X chromosome. When the term ''"autosomal recessive ocular albinism"'' ("AROA") is used, it usually refers to mild variants of oculocutaneous albinism Oculocutaneous albinism is a form of Albinism in humans, albinism involving the human eye, eyes (''wikt:oculo-#Prefix, oculo-''), the human skin, skin (''-wikt:cutaneous#Adjective, cutaneous''), and the hair. Overall, an estimated 1 in 20,000 peo ... rather than ocular albinism, which is ''X-linked''. __TOC__ Types References External links GeneReviews/NCBI/NIH/UW entry on Ocular Albinism, X-Linked {{DEFAULTSORT:Ocular Albinism Albinism Amino acid metabolism disorde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albinism In Humans
Albinism is a congenital condition characterized in humans by the partial or complete absence of Biological pigment, pigment in the skin, hair and eyes. Albinism is associated with a number of vision defects, such as photophobia, nystagmus, and amblyopia. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers. In rare cases such as Chédiak–Higashi syndrome, albinism may be associated with deficiencies in the transportation of melanin granules. This also affects essential granules present in immune cells, leading to increased susceptibility to infection. Albinism results from inheritance of Dominance (genetics), recessive gene alleles and is known to affect all vertebrates, including humans. It is due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin. Unlike humans, other animals have multiple Biological pigments, pigments and for these Albinism in biology, albinism is considered to be a hereditar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ã…land
Åland ( , ; ) is an Federacy, autonomous and Demilitarized zone, demilitarised region of Finland. Receiving its autonomy by a 1920 decision of the League of Nations, it is the smallest region of Finland by both area () and population (30,541), constituting 0.51% of Finland's land area and 0.54% of its population. Its only official language is Swedish language, Swedish and the capital city is Mariehamn. Åland is situated in an archipelago, called the Åland Islands, at the entrance to the Gulf of Bothnia in the Baltic Sea. It comprises Fasta Åland, on which 90% of the population resides, and about 6,500 Skerry, skerries and islands to its east, of which about 60–80 are inhabited. Fasta Åland is separated from the coast of Roslagen in Sweden by of open water to the west. In the east, the Åland archipelago is Geographic contiguity, contiguous with the Archipelago Sea, Finnish archipelago. Åland's only land border is located on the uninhabited skerry of Märket, which it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albinism
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and reddish pink or blue eyes. Individuals with the condition are referred to as albinos. Varied use and interpretation of the terms mean that written reports of albinistic animals can be difficult to verify. Albinism can reduce the survivability of an animal; for example, it has been suggested that albino alligators have an average survival span of only 24 hours due to the lack of protection from UV radiation and their lack of camouflage to avoid predators. It is a common misconception that all albino animals have characteristic pink or red eyes (resulting from the lack of pigment in the Iris (anatomy), iris allowing the blood vessels of the retina to be visible); this is not the case for some forms of albinism. Familiar albino animals include in-bred strains of laboratory animals (rats, mice and rabbits), but populations of naturally occurring albino animals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deafness
Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss that precludes a person from understanding spoken language, an audiological condition. In this context it is written with a lower case ''d''. It later came to be used in a cultural context to refer to those who primarily communicate with a deafness aid or through sign language regardless of hearing ability, often capitalized as ''Deaf'' and referred to as "big D Deaf" in speech and sign. The two definitions overlap but are not identical, as hearing loss includes cases that are not severe enough to impact spoken language comprehension, while cultural Deafness includes hearing people who use sign language, such as children of deaf adults. Medical context In a medical context, deafness is defined as a degree of hearing difficulties such that a person is unable to understand speech, even in the presence of amplification. In profound deafness, eve ... [...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] |
Nyctalopia
Nyctalopia (; ), also called night blindness, is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases. Night blindness may exist from birth, or be caused by injury or malnutrition (for example, vitamin A deficiency). It can be described as insufficient adaptation to darkness. The most common cause of nyctalopia is retinitis pigmentosa, a disorder in which the rod cells in the retina gradually lose their ability to respond to the light. Patients with this genetic condition have progressive nyctalopia and, eventually, their daytime vision may also be affected. In X-linked congenital stationary night blindness, from birth the rods either do not work at all, or work very little, but the condition does not get worse. Another cause of night blindness is a deficiency of retinol, or vitamin A1, found in fish oils, liver, and dairy products. The opposite problem, the inability to see in bright light, is known as hemeralo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Blindness
Color blindness, color vision deficiency (CVD) or color deficiency is the decreased ability to color vision, see color or differences in color. The severity of color blindness ranges from mostly unnoticeable to full absence of color perception. Color blindness is usually a Sex linkage, sex-linked Heredity, inherited problem or variation in the functionality of one or more of the three classes of cone cells in the retina, which mediate color vision. The most common form is caused by a genetic condition called congenital red–green color blindness (including protan and deutan types), which affects ''up to'' 1 in 12 males (8%) and 1 in 200 females (0.5%). The condition is more prevalent in males, because the opsin genes responsible are located on the X chromosome. Rarer genetic conditions causing color blindness include congenital blue–yellow color blindness (tritan type), blue cone monochromacy, and achromatopsia. Color blindness can also result from physical or chemical dam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichromacy
Dichromacy (from Greek ''di'', meaning "two" and ''chromo'', meaning "color") is the state of having two types of functioning photoreceptors, called cone cells, in the eyes. Organisms with dichromacy are called dichromats. Dichromats require only two primary colors to be able to represent their visible gamut. By comparison, trichromats need three primary colors, and tetrachromats need four. Likewise, every color in a dichromat's gamut can be evoked monochromatic light. By comparison, every color in a trichromat's gamut can be evoked with a combination of monochromatic light and white light. Dichromacy in humans is a color vision deficiency in which one of the three cone cells is absent or not functioning and color is thereby reduced to two dimensions. Perception Dichromatic color vision is enabled by two types of cone cells with different spectral sensitivities and the neural framework to compare the excitation of the different cone cells. The resulting color vision ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oculocutaneous Albinism
Oculocutaneous albinism is a form of Albinism in humans, albinism involving the human eye, eyes (''wikt:oculo-#Prefix, oculo-''), the human skin, skin (''-wikt:cutaneous#Adjective, cutaneous''), and the hair. Overall, an estimated 1 in 20,000 people worldwide are born with oculocutaneous albinism. OCA is caused by mutations in several genes that control the biosynthesis, synthesis of melanin within the melanocytes. Seven types of oculocutaneous albinism have been described, all caused by a disruption of melanin synthesis and all autosomal recessive disorders. Oculocutaneous albinism is also found in non-human animals. Types The following types of oculocutaneous albinism have been identified in humans. See also * Piebaldism * List of skin conditions * List of cutaneous conditions associated with increased risk of nonmelanoma skin cancer References External links Oculocutaneous albinism informationat RareDiseases.org NCBI Genetic Testing Registry {{DEFAULTSORT:Ocul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CACNA1F
Cav1.4 also known as the calcium channel, voltage-dependent, L type, alpha 1F subunit (CACNA1F), is a human gene. This gene encodes a member of the alpha-1 subunit family; a protein in the voltage-dependent calcium channel complex. Calcium channels mediate the influx of calcium ions into the cell upon membrane polarization and consist of a complex of alpha-1, alpha-2/delta, beta, and gamma subunits in a 1:1:1:1 ratio. The alpha-1 subunit has 24 transmembrane segments and forms the pore through which ions pass into the cell. There are multiple isoforms of each of the proteins in the complex, either encoded by different genes or the result of alternative splicing of transcripts. Alternate transcriptional splice variants of the gene described here have been observed but have not been thoroughly characterized. Mutations in this gene have been shown to cause incomplete X-linked congenital stationary night blindness type 2 (CSNB2). See also * Calcium channel A calcium channel is an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
