COLOR BLINDNESS

COLOR BLINDNESS NAME AYESHA KHANROLL NO 04SUBJECT - GENETICSFACULTY ANITA RAOCOLOR BLINDNESSColor blindness, orcolor visiondeficiency, is the inability or decreased ability to see color, or perceive color differences, under normal lighting conditions.

There is no actual blindness but there is a deficiency of color vision.

It is very rare that a person can't see colors at all, more likely that they can't distinguish shades of red, green, or blue.The Retina Contains Two Types of Light-Detecting CellsThe typical humanretinacontains two kinds of light cells: therod cells(active in low light) and thecone cells(active in normal daylight). Normally, there are three kinds of cones, each containing a different pigment, which are activated when the pigments absorb light.

These receptors are often called S cones, M cones, and L cones, for short, medium, and long wavelength; but they are also often referred to as blue cones, green cones, and red cones, respectively.

Different Types of Color BlindnessMonochromacy: occurs when two or all three of the cone pigments are missing and color and lightness vision is reduced to one dimension.

Total color blindness

Dichromacy: occurs when only one of the cone pigments is missing and color is reduced to two dimensions.

Partial color blindnessred-greenblue-yellow

Types There are two major types of color blindness: those who have difficulty distinguishing between red and green, and who have difficulty distinguishing between blue and yellow.RedgreenDichromacy (one of the three basic color mechanisms is absent or not functioning. It is hereditary)Anomalous trichromacy (one of the three cone pigments is altered in its spectral sensitivity)BlueyellowDichromacy (tritanopia)Anomalous trichromacy (tritanomaly)Different types of color blindness and how do they see the world

Deuteranomaly people only see a little green. A lot of colors dull and pinks turn almost completely purple.

Tritanomaly people only see a little blue. All the bright colors dull and bright green turns into a dull blue.

Protanopia people see no red at all. Blues dull, greens turn yellow, and reds turn brown.

Deutanopia people see no green at all. Reds come out a little more though, and blues are brighter.

Tritanopia people see no blue at all. They can see red perfectly fine, but blue turns much darker, almost blackish.

6How Color-Blind People See Things

NormalNormalNormalNormalNormalDefect in L-cone (poor red vision)Defect in M-cone (poor green vision)Defect in S-cone (poor blue vision)Causes GeneticsColor blindness can be inherited. It is most commonly inherited from mutations on theX chromosome.

Other causes

Other causes of color blindness include brain or retinal damage, accidents and other trauma which produce swelling of the brain in the occipital lobe, and damage to the retina caused by exposure toultraviolet light(10300nm).

Color blindness may also present itself in the spectrum of degenerative diseases of the eye, such as age-relatedmascular degeneration, and as part of the retinal damage caused bydiabetes. Another factor that may affect color blindness includes a deficiency inVitamin A.

9DiagnosisIshihara color test which consists of a series of pictures of colored spots, is the test most often used to diagnose redgreen color deficiencies. A figure is embedded in the picture as a number of spots in a slightly different color, and can be seen with normal color vision, but not with a particular color defect.

THE INHERITENCE PATTERNIt is a sex- linked trait when inherited (not acquired)Caused by a gene on the X chromosomeIt is a recessiveMore common in males.

Green Color Blindness

Gene OPN1MW GC0XP148439Start: 148,439,714 bp from pterEnd: 148,453,078 bp from pterSize:13,364 basesOrientation: plus strand

Red Color Blindness

Gene OPN1LW GC0XP147547Start: 147,547,307 bp from pterEnd: 147,561,950 bp from pterSize: 14,643 basesOrientation: plus strand

Punnett Squares for X-linked Traits:Why Color-Blindness is More Common in Males

Protein Affected

Rhodospin, the receptor protein in rod cells, crosses the disc membrane seven times. Its odd shape is shared by three receptor proteins in cone cells. Retinal (which absobs light) is shown in purple. The other balls (yellow) represent amino acids which make up the rhodospin structure.Chromosomes Involved in Color Blindness

Signs& SymptomsSymptoms may very from person to person.Different types of colorblindness exist in the world, in red-green color blindness, the colors of Red, Orange, Yellow, and Green, as well as all their shades will look the same to you.In other types of colorblindness you may not be able to see a certain color, or distinguish shades of color. Some people who are completely colorblind only see Black& White.

*Does not affect life expectancy*SymptomsRed-green : see colours differently and problems differentiating between different colour hues.

Blue-yellow : problem differentiating between blue and green.

No colour vision :can see only shades of white,grey, and black.TREATMENTColor Blindness Cure-Curing color blindness is currently impossible. 99% of color blind males and females are color blind as a result of defective genetics on the X chromosome. To cure this color blindness would require some form of gene therapy, repairing the damaged chromosome. Color Blindness Correction-Recent developments in light filtering lenses have made it possible to provide color blind people with a greater ability to distinguish between certain shades that otherwise look the same.Eye Care- care should be taken if exposed to sun light or exposed to chemicals every day .

Gene therapy (latest research)Recently research have been done to cure color blindness by gene therapy.

Gene therapy has successfully allowed red-green color- blind monkeys to see new colours that they have never seen before.

The first step in moving the treatment forward will be determining its safety for use in human patients.Latest news of color blindness in India Delhi: 600 DTC drivers colour blind Information Commissioner revealed | Updated: January 22, 2014 15:43New Delhi:Travelling by DTC bus? Think twice as about 600 drivers are alleged to be colour blind but still driving on the basis of fake medical fitness certificates.

This serious issue concerning safety of passengers has been brought to the notice of Delhi Chief Minister Arvind Kejriwal by Information Commissioner M Sridhar Acharyulu

Famous instances of color blindness Facebooks colour scheme is blue because its founder (Mark Zuckerberg) is red-green colour blind.

The auther Christopher Paolini is colour blind and so in his books made dragons colour vision different to that of normal humans so that their colour vision would match his own

Howiem andel is colour blind.THANK YOU