Genetic Causes of Colorblindness / Color Vision Deficiency (CVD)

Color blindness is primarily caused by genetic factors and is typically inherited. Here are the key points about the genetic causes and inheritance of color blindness:

Genetic Causes

Color blindness is usually caused by mutations in genes responsible for producing light-sensitive proteins in the retina’s cone cells. The main genes involved are:

• OPN1LW and OPN1MW: Mutations in these genes cause red-green color blindness, the most common form[1][3].
• OPN1SW: Mutations in this gene cause blue-yellow color blindness, which is rarer[3].

These genetic alterations affect the cones’ ability to perceive certain colors, leading to various types of color vision deficiencies.

Inheritance Patterns

Red-Green Color Blindness: This type is inherited in an X-linked recessive pattern:

• It primarily affects males because they have only one X chromosome[1][2].
• Females are usually carriers, as they need two affected X chromosomes to express the condition[2].
• A color blind father cannot pass the condition to his sons but will pass the gene to all his daughters[4].
• A carrier mother has a 50% chance of passing the gene to her children[4].

Blue-Yellow Color Blindness: This rare form is inherited in an autosomal dominant pattern:

• It affects males and females equally[3].
• Only one copy of the altered gene is needed to cause the condition[3].

Prevalence

• Red-green color blindness affects about 8% of males and 0.5% of females in Northern European populations[2][5].
• Blue-yellow color blindness is much rarer, affecting fewer than 1 in 10,000 people worldwide[5].

Carrier Status: Women can be carriers of red-green color blindness without showing symptoms. A carrier mother has a:

• 50% chance of having a color blind son
• 50% chance of having a carrier daughter[4]

In rare cases, a woman can be color blind if she inherits the gene from both parents[4].

Color blindness is a complex genetic condition with various inheritance patterns and types. Understanding these genetic factors is crucial for predicting and managing the condition across generations.

Citations:

[1] https://www.gsdinternational.com/news/the-genetics-behind-color-blindness-the-causes

[2] https://www.colourblindawareness.org/colour-blindness/causes-of-colour-blindness/

[3] https://medlineplus.gov/genetics/condition/color-vision-deficiency/

[4] https://www.colourblindawareness.org/colour-blindness/causes-of-colour-blindness/inherited-colour-vision-deficiency/

[5] https://medlineplus.gov/download/genetics/condition/color-vision-deficiency.pdf

[6] https://my.clevelandclinic.org/health/diseases/11604-color-blindness

[7] https://disorders.eyes.arizona.edu/disorders/color-blindness-red-green-partial

[8] https://www.sciencedirect.com/topics/veterinary-science-and-veterinary-medicine/color-blindness