What Are the Causes of Achromatopsia?

Achromatopsia is more commonly know as color-blindness, but there is much more to this condition than just the inability to discern colors. It can lead to the loss of other senses, and possibly other eye conditions as well.

Identification

• Achromatopsia is a defect that causes a general decrease in the person's vision, increasing sensitivity to direct sunlight and harsh, artificial light as well; it also affects the ability to differentiate colors, creating so-called color-blindness.
  Within the eye, there are nerves referred to as rods and cones. The cones are responsible for absorbing and transmitting the nerve impulses that create the brain's ability to conceive pictures and images, perceive colors and make out details. Achromatopsia is, essentially, damage to the cones.

Features

• Achromatopsia is primarily an inherited condition commonly caused by defects in the CNGA3, GNAT2 or the CGNB3 chromosomes. The retina is made up of three types of cones; red cones, blue cones, and green cones. Each cone is responsible for one part of the spectrum that allows the human eye to see complete images. Children born with defects in the above-mentioned genes also have an imbalanced distribution of cone cells and cannot perceive details or colors; children born with an insufficient amount of cone cells can result in partial achromatopsia.

Hidden Risk

• Occasionally, parents of a child with achromatopsia display no symptoms of the condition themselves. In order for a child to develop achromatopsia, it must be passed on by both parents. However, since the genetic defect that causes achromatopsia can lie dormant within a parent, it can be extremely difficult to detect.

Size

• Achromatopsia affects one birth out of every 40,000, and is more prevalent in societies where the marriage of blood relatives is common. In this instance, frequent intermarriage increases the risk of two sets of defective chromosomes being combined, leading to achromatopsia.

Effects

• A person with achromatopsia is likely to experience a weakening of one side of the body, as well as sensory diminishment (particularly with regards to smell and audio perception) on one side of the body.
  Achromatopsia can also lead to nystagmus, an uncontrollable tic that causes the eye to look side to side or up and down rapidly, repeatedly and without explanation.