Who has Hemophilia in the Pedigree that is Shown?

The way a trait is inherited is known as the inheritance pattern. The two main inheritance patterns are autosomal dominant and autosomal recessive. In autosomal dominant inheritance, the expression of a gene requires only one copy of the dominant allele. Thus, an affected individual can be either homozygous dominant (DD) or heterozygous (Dd). In autosomal recessive inheritance, both alleles of a gene must be recessive in order for an individual to be affected with the disorder. An affected individual who has the recessive phenotype is said to be homozygous recessive. Carriers who are not affected by the recessive condition but carry a copy of the recessive allele are labeled heterozygous.

Pedigree charts can depict and track these inheritance patterns. A pedigree example will be shown in the following paragraphs about an individual affected with hemophilia.

Hemophilia and Pedigree Charts

Hemophilia has an X-linked recessive inheritance pattern. This means that the gene responsible for the condition is located on the X chromosome. Females have two x chromosomes and are referred to as homozygous dominant (XX) or homozygous recessive (XX) in respect to an x-linked recessive allele. Men only have one x chromosome (and one y) and are classified as either hemizygous recessive (X^hY) or heterozygous (X^HY). Since a male who only has the Y chromosome but no X chromosome and only needs one recessive allele of hemophilia to exhibit the phenotype, this means that males are more often affected by hemophilia. A flowchart that describes the inheritance of X-linked recessive pedigrees will be included below. In hemophilia and other X-linked recessive traits, males who are colorblind are more commonly represented on a pedigree than females who are colorblind.

1. If the father is colorblind and the mother has normal vision, all of the sons will be colorblind, and all the daughters will have normal color vision. All of the daughters will be carriers. For an X-linked recessive allele, normal vision is dominant ( X^H
2. If the father has normal vision and the mother is colorblind, then all the sons will have normal color vision, and all of the daughters will be obligate carriers (have two recessive alleles, one from each parent)
3. If the father is colorblind and the mother is a carrier, then half of the sons will be colorblind, and half of the sons will have normal color, vision and half of the daughters would be homozygous dominant and half will have a recessive allele with normal vision.
4. If the father has normal vision and the mother is a carrier, then half of the sons will have normal while half of the sons will be colorblind while all of the daughters will be carriers.

The pedigree below reflects the Punnett square describing the inheritance pattern for an X-linked recessive trait. The male on the pedigree who is colorblind is shaded in.

                         ♀    ♂  
                    X<sup>H</sup>X<sup>H</sup>    X<sup>h</sup>Y
                   /      \    |
                  /        \   | 
               X<sup>H</sup>X<sup>H</sup>   X<sup>H</sup>Y   X<sup>h</sup>Y 

Tips and Expert Advice

If you are concerned that you or someone in your family may have hemophilia, several things you can do include:

• Talk to your doctor. They can help you get a diagnosis and discuss treatment options.
• Join a support group. This can help you connect with other people who have hemophilia and learn more about the condition.
• Educate yourself about hemophilia. The more you know about the condition, the better you can manage it.

By following these tips, you can live a full and active life with hemophilia.

Image: www.numerade.com

Frequently Asked Questions

What is Hemophilia

Hemophilia is a rare genetic disorder that affects the blood’s ability to clot properly, causing excessive bleeding even after minor injuries.

What are the symptoms of hemophilia?

The symptoms of hemophilia can vary depending on the severity of the condition. Common symptoms include:
– Easy bruising
– Prolonged bleeding from cuts or injuries
– Nosebleeds
– Joint pain and swelling
– Blood in the urine or stool

How is hemophilia diagnosed?

Hemophilia is diagnosed with a blood test that checks the clotting ability of the blood.

How is hemophilia treated?

There several treatments available for hemophilia which includes getting clotting factor replacement therapy, taking medication to prevent bleeding, avoiding activities that could cause injury, and wearing a medical ID bracelet or necklace.

Who Has Hemophilia In The Pedigree That Is Shown

Conclusion

If you are learning how to read and understand pedigrees, it is important to note that the symbols on a pedigree can mean different things depending on the disorder that is passed down through a family tree. This article demonstrated one pattern of inheritance which is x-linked dominant, but a pedigree designed to trace a dominant allele is different than the pedigree explained in the prior paragraphs. Understanding the symbols and patterns are vital to properly creating a pedigree chart.

If you have found this article informative, please share it with others so they may learn about pedigree charts. While you are on the page, check out the other great articles about understanding genetics and pedigrees at the bottom of the page.