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Heterochromia iridum. Heterochromia is a variation in coloration most often used to describe color differences of the iris, but can also be applied to color variation of hair [1] or skin. Heterochromia is determined by the production, delivery, and concentration of melanin (a pigment ). It may be inherited, or caused by genetic mosaicism ...
The irises of human eyes exhibit a wide spectrum of colours. Eye color is a polygenic phenotypic trait determined by two factors: the pigmentation of the eye 's iris [1] [2] and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris. [3] : 9. In humans, the pigmentation of the iris varies from light ...
1 in 100,000. Blue cone monochromacy ( BCM) is an inherited eye disease that causes severe color blindness, poor visual acuity, nystagmus, hemeralopia, and photophobia due to the absence of functional red (L) and green (M) cone photoreceptor cells in the retina. BCM is a recessive X-linked disease and almost exclusively affects XY karyotypes.
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.
Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or one blue eye and one brown eye ), a white forelock or patches of light skin. These basic features constitute type 2 of the condition; in type 1, there ...
Ophthalmology. Usher syndrome, also known as Hallgren syndrome, Usher–Hallgren syndrome, retinitis pigmentosa–dysacusis syndrome or dystrophia retinae dysacusis syndrome, [1] is a rare genetic disorder caused by a mutation in any one of at least 11 genes resulting in a combination of hearing loss and visual impairment.
Gene therapy for color blindness is an experimental gene therapy of the human retina aiming to grant typical trichromatic color vision to individuals with congenital color blindness by introducing typical alleles for opsin genes. Animal testing for gene therapy began in 2007 with a 2009 breakthrough in squirrel monkeys suggesting an imminent ...
Researchers have found a link between semaglutide use and NAION, a rare condition that is the second-leading cause of optic nerve blindness. (Getty Images) (Jacob Wackerhausen via Getty Images)