Question

A cross between a normal couple resulted in a son who has haemophilic and a normal daughter. In the course of time when the daughter was married to a normal man , to their surprise the grandson was also haemophilic.
(A)Represent this in the form of a pedigree chart.Give the genotypes of the daughter and husband.
(B)Write the conclusion you draw of the inheritance pattern of this disease.

Answer 1

Hint: Haemophilia is a genetic condition often inherited that impairs the ability of the body to make blood clots, a process necessary to avoid bleeding.
A pedigree chart is a diagram that indicates the frequency and appearance of phenotypes from one generation to the next of a single gene or organism and its ancestors, most often humans, show dogs, and race horses.

Complete answer:
(A)Pedigree Chart:
For two or more generations, pedigree analysis is a record of the inheritance of a genetic trait. In the form of a diagram or map or family tree, it is presented. It is used in the case of humans and domesticated animals, especially pets.
The mode of inheritance of a variety of diseases and characteristics such as haemophilia, colour blindness, syphilis, insanity, rheumatism, hysteria etc among children can be predicted by pedigree study. It is traditional to use circles for women and squares for males in a pedigree map.
The most infamous of all sex-linked diseases is haemophilia or the "royal disease". It is also widely referred to as bleeder's disease because the person suffering from this disease (haemophiliacs) bleeds for a very long time (from 1/2 to 22 hours or more) without blood coagulation on sustaining a minor injury.

Genotype of daughter-\[X{{X}^{h}}\]
Genotype of husband- XY

(B)Conclusion :
Haemophilia is a recessive disorder that is sex-linked.It is transmitted here from the female carrier to the sons.From the above pedigree table, it can be observed that the disease is transferred from the female carrier to her daughter (carrier) and son (affected). The carrier's daughter is passing this illness on to her grandson. This inheritance pattern is called criss cross inheritance .

Note: Hemophilia can affect the lives of individuals in the family in many different ways. This is attributable to distinct haemophilia lifestyles and therapies. For example, since he could not get help when he was young, a grandfather with haemophilia could have really bad joints and walk with a limp. Since early factor therapy has kept his joints stable, his grandson will run track on his high school team.