Diseases

Daltonism: the causes

The causes of color blindness are 100% genetic. What simplifies understanding is that the gene in question is unique. It is carried largely by the X chromosome.

The gene, implicated in daltonism, is "recessive", which means that it will not express itself if it is carried by a single chromosome. In this case, the daltonism will be "hidden" by the so-called "healthy" gene. The gene becomes active only if it is present on both X chromosomes. Children inherit a maternal chromosome and a paternal chromosome.

For years, confusion has led to the belief that girls can not be color-blind. And yet, this is possible, even if it is rare since only 0.5% of women are affected by color blindness, against 8% of men.

Here are the different possible cases of transmission:

Case 1
Mother (X chromosome carrying the gene) + Father (normal X chromosome) => Non-color-blind girl

Case 2
Mother (normal X chromosome) + Father (chromosome X carrying the gene) => Non-colorblind girl

Case 3
Mother (X chromosome carrying the gene) + Father (normal Y chromosome) => Colorblind boy

Case 4
Mother (chromosome X carrying the gene) + Father (chromosome X carrying the gene) => Colorblind girl

In summary, the causes of daltonism are reduced to the influence of a single gene. The latter is active when it is present on the X chromosome of a boy, or on both X chromosomes of a girl.

You want to react, to give your testimony or to ask a question? Appointment in our thematic FORUMS or A doctor answers you!

Popular Posts

Category Diseases, Next Article

Anal fissure: Treatments - Diseases
Diseases

Anal fissure: Treatments

The anal fissure is benign in most cases, provided it is diagnosed in time. But, located in an intimate area, consultation is often delayed. In addition, if your general practitioner is able to examine you from head to toe, it happens that an anal fissure is first diagnosed as hemorrhoids, which delays the management
Read More
Encephalitis: causes - Diseases
Diseases

Encephalitis: causes

The precise causes of toxemia of pregnancy are poorly understood. Primiparous women, that is, having their first pregnancy, are the most affected by this disorder. Among the causes, the reasons for toxemia of pregnancy include placental insufficiency which is an abnormality that can occur in the first trimester of pregnancy, but there is no early way to detect it
Read More
Hashimoto: sources and notes - Diseases
Diseases

Hashimoto: sources and notes

Author: Dr Iléana de Lameth, Hospital Practitioner in Endocrinology, Diabetology, Nutrition Sources: 1. High Authority of Health (HAS). Hypothyroidism in adults: Diagnosis and care April 2007. www.has-sante.fr/portail/upload/docs/application/pdf/hypothyroidies_frustes_recommandations_vf.pdf 2. Biological diagnosis and monitoring of adult hyperthyroidism February 2000 //www.
Read More
Zika: the transmission - Diseases
Diseases

Zika: the transmission

The Zika virus is transmitted to humans through bites of an infected mosquito of the genus Aedes. This mosquito, also called tiger mosquito, exists in tropical and subtropical regions and also transmits dengue, chikungunya and yellow fever. The transmission of the virus can also be done in the other direction
Read More