The color perception defect manifests itself in females only when it is inherited from both parents. By contrast, males inherit their single X-chromosome from their mothers and become red green color blind if this X-chromosome has the color perception defect. Different genotypes for this trait are illustrated below. Since males have only one X-chromosome, if this chromosome has the red-green color blind allele, the males will have the color perception defect.
Genes on the X chromosome can be recessive or dominant. Their effect in males and females is not the same.
For males, there needs to be only one copy of a nonworking gene on their 1 copy of the X chromosome for the trait or disorder to appear. Females are generally not affected unless both copies of the gene one on each X chromosome are not working.
Females who carry only 1 copy of an affected gene may not have any symptoms of the condition or may show mild symptoms compared with males. There is a 1 in 2 chance that daughters carry the gene and can pass it to the next generation. There is a 1 in 2 chance that a daughter will not carry the gene and so cannot pass it on. There is a 1 in 2 chance that sons don't have the gene and will be healthy. Simply put, yes, color blindness is a hereditary condition.
The genetics of exactly how heritable color blindness moves through families, however, can be quite complex. Most commonly, color blindness is inherited as a recessive trait on the X chromosome. For example, a woman can carry a recessive gene on one of the X chromosomes unknowingly, and pass it on to a son, who will express the trait:.
Click Image to Enlarge. Red-green color blindness. Red-green color blindness means that a person cannot distinguish shades of red and green usually blue-green , but their ability to see is normal. There are no serious complications; however, those affected may not be considered for certain occupations involving transportation or the Armed Forces where color recognition is required.
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