SNP Shot: Genomic Insights

Color vision deficiency, often referred to as color blindness, encompasses a range of conditions impacting the ability to perceive colors accurately. The most prevalent type involves difficulty distinguishing between shades of red, yellow, and green, known as red-green color vision defects. Rarer blue-yellow color vision defects (tritan defects) make it hard to differentiate between shades of blue and green, and to tell dark blue apart from black. While these conditions affect color perception, they don't impair visual acuity (sharpness of vision).

A less common and more severe type of color vision deficiency, blue cone monochromacy, results in significantly reduced visual acuity and severely impaired color vision. Individuals with this condition often experience additional vision issues such as increased light sensitivity (photophobia), involuntary eye movements (nystagmus), and nearsightedness (myopia). Blue cone monochromacy is sometimes classified as a form of achromatopsia, which is characterized by a partial or complete absence of color vision accompanied by other visual impairments.

Inheritance:

Red-green color vision defects and blue cone monochromacy are inherited through an X-linked recessive pattern. The OPN1LW and OPN1MW genes are situated on the X chromosome, one of the two sex chromosomes. Males, possessing only one X chromosome, need only one altered gene copy in each cell to develop the condition. X-linked recessive disorders affect males much more often than females because females, with two X chromosomes, would require a genetic change on both copies of the chromosome to be affected. A defining feature of X-linked inheritance is that fathers cannot transmit X-linked traits to their sons. Blue-yellow color vision defects follow an autosomal dominant inheritance pattern, meaning that just one copy of the altered OPN1SW gene in each cell is enough to cause the condition. Frequently, an affected individual inherits the condition from a parent who also has it.