Mating of a hemophilic male (XhY) to a normal female (XHXH) results in a normal son (XHY) and a carrier daughter (XHXh) in the F1 progeny. Intermarriage between F1 progeny resulted in F2 progeny with 1 normal son, 1 hemophilic son, 1 normal daughter and 1 carrier daughter.

Hemophilia causes abnormal bleeding from muscles, digestive tract, urinary tract, teeth, nasal cavity etc. There is no readily available treatment. 75% of hemophilia has no treatment. America has developed some expensive medical treatments through biotechnology.

(1) Fibrinogen, (2) Prothrombin, (3) Thromboplastin, (4) Calcium ion, (5) Labile, (6) Axillarin, (7) Proconvertin, (8) Antihemophilic, (9) Christmas, (10) Stewart , (11) PTA, (12) Hageman and (13) Lecky.

1. Classic Hemophilia or Hemophilia A: Hemophilia A is caused by the absence of the 8th antihemophilic factor in blood clotting. 80% of affected patients have hemophilia A.
2. Christmas Haemophilia or Haemophilia B: Haemophilia B is caused by the absence of Christmas, the 9th clotting factor. 20% of affected patients have hemophilia B.

1. Continuous bleeding from the wound.
2. Blood does not clot.
3. Internal bleeding occurs anywhere in the body.
4. Bleeding into the joints during exercise or running (hemarthrosis).
5. Joints become swollen and painful.
6. Abnormal bleeding occurs from muscles, digestive tract, urinary tract, teeth, nasal cavity etc.

Haemophilia is caused by a latent mutant gene (h) located on the human chromosome. Hemophilia is caused by a deficiency of human blood clotting factors antihemophilic and Christmas.

Hemophilia is a fatal sex-linked disease. The disease is inherited by a recessive gene on the human X chromosome. When erogenous, the wound bleeds continuously and the blood does not clot. Erosion can lead to death. It is called criss-cross disease as the disease is transmitted from father through daughter to grandson.

Hemophilia is called the royal disease. Of the nine children of Queen Victoria of England (1837–1901), two daughters, Alice and Beatrice, were carriers of the hemophilic gene. Of Alice’s two daughters, Tsarina Alexandra was married to Prince Nicholas of Russia and Irene to Prince Heinrich of Germany. Beatrice’s daughter Victoria was given in marriage to King Alfonso of Spain. As a result, the disease spread through the royal family. Hence it is called royal disease. The latent hemophilia gene is inherited from father through daughter to grandson i.e. follows the criss-cross transmission principle.

A normal male (XY) married to another color blind (XcXc) female produces a color blind son (XcY) and a color blind carrier daughter (XcX) in the F1 lineage. Intermarriage between the F1 progeny results in F2 progeny with 1 normal son, 1 normal daughter, 1 color blind son and 1 color blind daughter.

here,

A normal male has a genotype of XY

Genotype XcXc of a color blind woman

The first progeny is F1 and the second progeny is F2

Parents :           ♂     ×             ♀

Phenotype: Normal       color blindness

Genotype :       XY             XcXc

Gamit :        (X) (Y)         (Xc) (Xc)

F1 Generation : XcX XcY

 

Self fertilization : F1×F1

Parents :              ♂         ×     ♀

Phenotype:  color blind      carrier

Genotype :         XcY         XcX

Gamit :          (Xc) (Y)    (Xc) (X)

F2 Generatin (checker board)

Comment: From the checker board, out of 4 children, 1 normal son, 1 normal daughter, 1 color blind son and 1 color blind daughter. Color blindness requires one Xc gene in males and two Xc genes in females.

Phenotypic Ratio : Normal Son : Normal Daughter : Color Blind Son : Color Blind Daughter = 1:1:1:1

A colorblind male (XcY) married to a normal (XX) female produces an F1 offspring with a normal son (XY) and a colorblind carrier daughter (XcX). Intermarriage between the F1 offspring results in 1 normal son, 2 normal daughters and 1 color-blind son in the F2 progeny.
here,
Genotype XcY of a color blind male
A normal female has a genotype of XX
The first progeny is F1 and the second progeny is F2

Parents : ♂ × ♀
Phenotype: Normal color blindness
Genotype : XcY XX
Gamit : (Xc) (Y) (X) (X)
F1 progeny : XcX XY
(carrier daughter) (natural son)
Svanishek : F1×F1
Parents : ♂ × ♀
Phenotype: Normal carrier
Genotype : XY XcX
Gamit : (X) (Y) (Xc) (X) )
F2 progeny (checker board)
Comment: From the checker board, out of 4 children, 1 normal son, 2 normal daughters and 1 color blind son. Color blindness requires one Xc gene in males and two Xc genes in females.
Phenotypic ratio : Normal son : Normal daughter : Color blind son = 1 : 2 : 1

The mutation stops the development of the color-sensitive cells in the human retina, and people with the latent gene cannot distinguish particular colors. It is called color blindness. John Dalton described human color blindness. It is called Daltonism. 95% of color blind people are red-green color blind. There is no cure for color blindness or people who are color blind are never cured. The best test for color blindness is the Ishihara color test.