Is color blindness hereditary? What are the types?

Color blindness is a disease. Patients cannot distinguish between red, yellow, blue and green, and often see one color as other colors. This is due to chromosomal lesions, which cause abnormal gene color distinction and weakening of bright colors. The brighter the color, the harder it is to see. There are many types of color blind patients. Total color blindness is a more serious disease disorder because it only affects one color. Different types require different treatments. Color blindness is somewhat hereditary.

Clinical manifestations

It is generally believed that red and green color blindness is determined by two pairs of genes on the X chromosome, namely the red and green color blindness genes. Because these two pairs of genes are tightly linked on the X chromosome, they are often represented by one gene symbol. Red and green color blindness is inherited in an X-linked recessive manner. Males only have one X chromosome, so they only need one gene to be color blind. Females have two X chromosomes, so they need a pair of disease-causing alleles to show abnormalities. If a normal woman marries a color-blind man, the father's color-blind gene can be passed on to their daughter via the X chromosome, but not to their son. The daughter then passes the color blindness gene from her father to her son, a phenomenon called cross-inheritance.

Color blindness is divided into total color blindness and partial color blindness (red color blindness, green color blindness, blue-yellow color blindness, etc.). Color weakness includes total color weakness and partial color weakness (red weakness, green weakness, blue-yellow weakness, etc.).

1. Achromatopsia

It is a complete cone cell dysfunction, which is the opposite of night blindness (rod cell dysfunction). Patients prefer darkness and are afraid of light, which manifests as day blindness. There is only a difference in light and dark, but no difference in color, and the red appears dark and the blue appears bright. In addition, there are symptoms such as poor vision, amblyopia, central scotoma, and pendulum nystagmus. It is the most severe form of color vision deficiency and is less common.

2. Red-color blindness

Also known as the first color blindness. The patient is mainly unable to distinguish the color red, and cannot distinguish red from dark green, blue from purple-red, and purple. Green is often seen as yellow, purple is seen as blue, and green and blue are mixed as white.

3. Deuteranopia

Also known as second color blindness, patients cannot distinguish between light green and dark red, purple and cyan, purple and gray, and perceive green as gray or dark black. In clinical practice, red-green color blindness and green-color blindness are collectively referred to as red-green color blindness, which is more common. The color blindness we usually talk about usually refers to red and green color blindness.

Color blindness is called color vision disorder, which is the inability to distinguish various colors or certain colors in the natural spectrum; color blindness is mostly caused by congenital factors. There are far more male patients than female patients. Surveys show that the prevalence of color blindness among Chinese men is 7.0‰, and among women it is 0.5‰. Here we will mainly talk about the relationship between color blindness and genetics.

How is color blindness inherited?

Modern genetic research suggests that color blindness is inherited in a sex-linked manner. It turns out that the sex chromosomes in human cells are divided into X chromosomes and Y chromosomes, with the XX chromosome combination being female and the XY chromosome combination being male. The human color gene is present on the X chromosome, but not on the Y chromosome.

According to Mendel's law of inheritance, since the color blindness gene is a recessive gene and the normal color vision is a dominant gene, women with normal color vision may also have a recessive color blindness gene. If both parents have normal color vision genes, the offspring will not be color blind; but if both parents have normal color vision and the mother has a recessive color blindness gene, the offspring may have normal color vision or may be color blind. For a woman to be color blind, she must have two identical recessive genes at the same time, but the chance of this happening is rare after all. Men only have one X chromosome, so they are more likely to suffer from color blindness. No wonder there are significantly more male color blind people than females.

Treatment for color blindness

Although color blindness is a genetic disease, it does not directly endanger human life or cause physical disability like some genetic diseases. What we need to do is to avoid causing greater impact on patients' career choices, physical and mental health, etc. Currently, color blindness correction glasses and visual training are mainly used to make people who were originally unable to recognize color pictures correctly recognize them. Achieve the effect of correcting color vision impairment.